"I enjoy watching children," she said. "It comforts me to remember that I too was a child once, and one day they too will be old."

Her shiny olive skin was firm, but even the best youth-treatments couldn't hide the purple veins that snaked around her arms like cables. She appeared to be in well-preserved middle-age; only I and a few other agents knew the truth. Her eight remaining fingers were casually laced over a knobby walking stick that she carried for show. A particularly knowledgeable observer might have noted that the cherry-red wood was at once lighter and stronger than any known on Earth. Dr. Constance Roya was a scientist in the ancient sense, when that term implied at least as much of a reckless love for adventure as an appreciation of form and method and the furtherance of human knowledge.

I turned my gaze from Dr. Roya to the park below. Children from the nearby ambassador's school scrambled over banyan tree roots, hanging and swinging so adroitly that it suddenly seemed the separation between humans and apes was not so great as we liked to imagine.

I said as much to Dr. Roya. Her answering smile was brief and indulgent. I had a sudden impression of those dark, full lips breaking me open, holding their silence.

"They're children," she said, her voice incongruously deep and carrying for such a small body. "Ontogeny recapitulates phylogeny . . ."

I stared—was she playing me? She laughed and shrugged.

". . . Except when it doesn't, Mr. Smith." I had told her my name. But she insisted on denying me what little individuality I had left. Could I blame her? She saw the agency acronym on my lapel; she knew what I'd come for.

"Dr. Roya, I think it's time you showed me the lab," I said, hoping, like a child, to hurt her with my authority.

She smiled again; I flinched. "A moment, Mr. Smith." I saw her clearly, then: beautiful and terrible, ancient and radical, a goddess as much as any human can be. Killing a hexapedal carnivore with a hand-made spear, hiding for two days from a giant amphibious jellyfish desperate for food, surviving alone in the Well for five years before the computers on this side even registered the malfunction—those rumors had floated around the agency for decades. I'd found it impossible to believe that such a small, unassuming woman had done all they said she did.

Now? Evidence acquired, knowledge attained, theory proven. Evolution occurred; Constance Roya could eviscerate me with a glance. QED. I took a step back.

"Do you know what those are?" she said, gesturing again to the park below.

I hesitated. She couldn't be referring to the children. So that left . . . "Ficus benghalensis?"

She raised an eyebrow. "An invasive species," she said. "Like a bureaucrat."

"I'm not—"

She began walking toward the elevator. She held her spine like a steel rod, her walking stick like a bludgeon. "Of course you are," she said, her voice brittle as fossilized bone. "With just enough knowledge to destroy the world."

Dr. Roya flicked on the lights. I expected a clinical fluorescent glow, but the light that filled the room was warm and dappled, as though glancing off summer leaves. It seemed, for a moment, like I could smell the fresh cut grass, evaporating dew, nightsoil fertilizer from the surface a hundred floors above.

"You convinced building services to pump in sunlight?" I said. But you couldn't smell sunlight.

Dr. Roya closed her eyes. I could hear the air whistling into her lungs. "It's the only way I can work," she said, after a moment.

I took a discreet sniff. Just normal lab smells: alcohol and preserving chemicals, carpet cleaner, laundered lab coats, disposable gloves. The door to the Well airlock, marked with yellow paint and prominent security touchpads, smelled like nothing at all.

She gave me a quick glance and walked to a recessed door on the far right. To each side hung one of Dr. Roya's legendary illustrations: chimeras and monsters, living fossils and mythic beasts, all drawn to minute anatomical detail. I saw a spray of razor-sharp hairs in the nail bed of a giant flying sloth, perfectly designed to slowly bleed its airborne prey to death before landing. On the other side hung an image that made me shudder, though I had studied it for hours when it first came across the classified feeds. A pair of gigantic red lips, disembodied from any suggestion of a face, washed up on a beach. It had multiple digestive pockets in the lining of its massive mouth, where it could store small sea creatures for weeks like fish in the window of a Chinese restaurant.

Dr. Roya had opened the door, but walked back to where I stood, frozen before her pictures.

"It climbed out of the water," she said, pointing to the mouth. "On its lips. I thought it was going to eat me, but it died. I hacked it open with a stone knife after I drew this." She paused, with a wry smile I supposed she meant for herself. "This creature had a neural net the size of my thumbnail, but it went to a beach to die." She shook her head. "I brought back samples for the lab, but they rotted by the time you fellows rescued me. I've never been able to find it again. Hell, it probably went extinct ten minutes after I left."

I caught something in her voice I recognized, though it took me a moment to place. Some mutant hybrid of envy, wistfulness, and grief. The way I'd felt when I had dropped out of graduate school and taken a post at the agency.

I tried, "It seems like such . . ."

"A waste," she finished. Her voice was uncharacteristically gentle. "Like most treasures."

She let me stare for a few more seconds and then strode back to the open door. "Well, come on. You should at least see everything."

I followed her through. The light here was low and ambient, the temperature a chill twenty degrees Celsius. To my right and left rested shelf after shelf of specimens, some preserved in makeshift camp jars and others floating in specially-made aquariums that preserved anatomical detail down to the organelles. Standing there, dwarfed by the entire recorded biology of an alien ecosystem, I felt close to hyperventilating. Bug-eyed fish with prehensile fins, meter-thick tree limbs with giant blue leaves for wings and purple fruit for retractable eyes, millipedes as long as my body and thicker than my torso, with each segment differentiated into a cascade of arms.

I had avoided museums since quitting school, though I made a hobby of collecting illustrations. But standing here among thousands of extinct species that were only a fraction of a fraction of the species even now going extinct, old school day terrors rushed back. I felt as though time itself could crush me. I did not feel awe or joy or any transcendent moment of the scientific understanding of Einstein's god. No, I was a peon again, terrified by the breadth of the universe, by my utterly insignificant place in it, by the eternity of my death and that of everyone I loved. The room swayed. I closed my eyes.

"Oxaloacetate, Citrate, cis-Aconitate, Isocitrate," I whispered, letting my mind go blank.

"The Krebs cycle as catechism?" Her voice was at my elbow. "No wonder they sent you to do this job."

I forced myself to open my eyes. For some reason, her presence was reassuring. Or at least intimidating in a far less existential way. "I begged them," I said. Cracking myself open, hoping she would understand I wasn't just another Mr. Smith.

She touched my sleeve. It was meant for comfort, but my pulse jumped. "So eager to put an old scientist out to pasture?"

I shook my head. "I just wanted to meet you. If someone had to do it . . ."

"Better someone who understands my work? I should show you something."

Around the corner from the specimens, a floor-to-ceiling clear plastic wall separated us from a waterless aquarium. Aside from a slime mold growing on the floor, the chamber was empty.

"Now look," Dr. Roya said. Her voice seemed closer to a twelve-year-old girl's, ecstatic with her first discovery of a toad in the garden. She turned down the lights.

Suddenly, the room that had been empty was teeming with life. Ghostly obloid creatures, organs lit up like lights in a Christmas show, swam through the air. They were buoyed by a thick fringe of cilia that beat the air like a broom. Paramecia a handspan across?

Dr. Roya pressed her face against the smudge-proof plastic. In such low light her treated skin was translucent as tracing paper; I could see a vein throbbing in her forehead. She was eighty-seven years old, give or take a few weeks, according to the agency calculators. But she had been born just ten years before me. The Well extracted its price.

"Single cells," she said, in response to my unvoiced question. "They existed, briefly, in Earth's past. I happened to catch some evolving during phase one."

"In the air?"

"No, no, the project was at least a hundred million years away from getting out of the oceans. I brought them back here, did some old-fashioned genetic engineering. I knocked out genes until my assistants threatened to quit. I took it as far as I could, and what do you know . . ."

One paused before us, shuddered—like a dog shaking off mud—and suddenly split in two.

"Could they . . . do you think they could self-organize?"

She closed her eyes, like the concept almost overwhelmed her. "The oxygen content of the atmosphere might pose technical limitations. But it's possible. Even your bosses can grasp that much."

I knew what she meant. The infinite possibility of time.

"I have some forms," I said, awkwardly, when we went back into the lab.

She laughed. "Of course. 'I hereby agree to sign my life away and bother you no more.' That kind of thing?"

The muscles in my neck felt taut, but I tried to smile. "That's the agency for you. Always signed in someone else's blood."

I had hoped to impress her, but her only response was to take the scroll and quickly tap through the documents. Tediously long, as though they meant to bury their intentions under piles of legalese. And no need for her to pay very close attention, as we both understood what they wanted.

"Oh look," she said, when she reached the end, "they've already put my pension into a retirement home. India. How thoughtful."

I dimly registered her venom, but she had triggered a memory—fellow agents making joking references to "Indian hospitality" and "nurse wards" for certain classes of dissidents. My clearance wasn't high enough to know what exactly happened to these people, but you couldn't work in the agency—even as the humblest clerk in the dullest Science division—without catching the general theme of the proceedings. And that theme was grim, bureaucratic, occasionally cruel and always merciless.

"There, you can tell your masters I cooperated." She tempered it with a smile, but I knew her words were deadly serious. I replaced the scroll in my jacket pocket. She took a few steps away from me, and then began to turn in a circle. Her eyes glittered as they surveyed the room. Her shoulders stiffened. She gripped her stick as though she really would fall down without it.

Then she sighed, a sudden and profound release of tension. "Well then, I guess there's just one thing left. You'll have to decontaminate, of course."

I hadn't expected it. I had hoped, like a child hopes for a bicycle on Christmas, but I'd known better than to expect it. No one at the agency had said I needed to inspect the Well. Dr. Roya guarded its access so notoriously I'm sure it never even crossed their minds that she would offer. She gave me no chance to fumble for words of incoherent gratitude. She hadn't used my name, but she would have never shared this with Mr. Smith. She understood.

She pressed her finger against the security touchpad and punched in a long string of numbers. Behind us, the seal around the main lab door expanded to create a quarantine-ready lock. It wouldn't open again until the computers confirmed the room was free of dangerous Well contaminants. Dr. Roya held up her right eye for a biometric scan. The door before us slid open with a slight exhalation of compressed air, like a sigh. It shut as soon as we walked inside. We were in the clean room, barely five feet away from the Well's red gate.

She pulled three long pins from her bun and let them plunk to the ground. Her hair, silvered and wavy, settled around her shoulders. She was halfway through unbuttoning her blouse before I realized I had to undress to decontaminate. I'd seen it done before, just not so informally. Hastily, I pulled off my jacket and loosened the strangling tie.

Dr. Roya, naked except for her underwear, clucked her tongue. "The only office in the country that still makes men wear nooses."

Beautiful and terrible. My emotions at the sight of her naked body shocked me. Her skin was taut and painfully thin. I felt as though I could see every corded vein and muscle, every hand-stitched scar, every coffee-stain of age. It should have been grotesque. It wasn't. I'd always thought I understood the difference between admiration and love. But it seemed they shared a common genetic ancestry. I hurriedly disrobed. Naked as a prelapsarian Adam and Eve, we washed in the chemical waters and donned our sterile clothing. I pulled on the supple, practical hiking pants and sweater. Dr. Roya adjusted a knapsack on her slight shoulders. In her left hand she carried her walking stick, in the other a strange metal box that had been waiting in the airlock. I looked at the bright red door ahead of us, surrounded by lights and accompanying touchpad displays. This was the gate. Just beyond: the Well. It was supposedly dangerous to go in without one person waiting Earth-side, but in truth the computers were much quicker at diagnosing problems than humans. I was sure Dr. Roya had done this alone dozens of times. I could tell as much from her alert, almost anticipatory posture.

"Ready?" she asked me, but she meant to go no matter what I said. So I nodded. "Willing, even when terrified. I would have liked you as a graduate student." She grinned.

And suddenly, the clanging inside my head was caused by so much more than arousal and fear. Dr. Roya was the greatest biologist of her age. And I, confronted with the slow-grazing terror of phylogenetic trees, the infinite subtle twistings of evolution's roots, had thrown it all away. Maybe everyone has existential crises. Especially scientists. But I hadn't been strong enough to get through it. And now I was just a drop-out. A faceless drone sent to destroy a woman he worshipped.

She handed me a facemask. "Air filters in case the atmosphere's gone toxic again. It shouldn't have. I think I've managed the equilibrium, but better safe. When the doors open, you'll see a ball of red yarn. Grab it and walk through. You'll feel like you're falling off a building. Then we land."

I nodded, too caught up to dare use my voice.

But hers was clear and defiant, like the last rally of a defeated general. "Open the door," she said.

The red parted onto absolute black. The yarn nestled like an egg against the void.

We stepped into the Time Well; we fell off the earth.

Once, one of the fellows from Physics—deeply ambitious but possessed of a quaint fondness for the scientific method—had tried to explain to me how the Time Well worked. You crossed into negative space, he said, into the paper-thin separation of our brane and the next. Then negative energy stabilized a wormhole that opened directly onto another planet. But time in the brane-universe moved faster. I had the vague idea that this had something to do with relativity: despite the fact that information from the brane-universe could travel here almost instantaneously, it took thousands of years for us to communicate back. Twenty-three Earth days for every million brane years, to be precise.

The physicists hadn't known what to do with the useless hunk of Venus-like rock when they first mapped the path through the wormhole. So they turned it over to Science Administration. And Constance Roya, who had just received her doctorate from Harvard, heard about the project and had an idea. Just give her access to the rock, she said, and she could turn it into a habitable planet. Only she had recognized the potential of the radical time scale shift. Only she had realized that time could turn this planet into something biologists had only dreamed of for centuries: evolution in a lab.

We landed on red, muddy earth. I stumbled to my knees. Behind me, the yarn seemed to vanish in midair. I fumbled to check my facemask, but stopped when I saw that Dr. Roya had already removed hers.

"Twenty-one percent oxygen," she said, a steward's satisfaction in her voice. She pocketed the tiny chemical scanner.

I stood up slowly. We had landed on some kind of mud flat. In the distance I could make out a smudge of ocean. We were surrounded by bright blue hillocks of slimy, interconnected filaments. I shielded my eyes and looked up: the star was large and reddish orange, the sky silvered white. I had read about this: the planet orbited a relatively hot M-class star. Photosynthetic pigments here absorbed the abundant red light, but reflected blue. Blue trees, I thought, almost dizzy with excitement.

"Come," Dr. Roya said. She started hiking across the mud flats. The metal box seemed heavy, but I didn't dare offer to carry it. I followed her to the gently undulating plain of thigh-high blue grass, unspooling the red yarn as I went. The grass smelled surprisingly similar to earth's, but as she beat it down with her stick I caught a whiff of something sweet and unexpected, like anisette. We hiked to a hill a few hundred yards distant, where the grass grew more sparsely. From this vantage point we could see for several kilometers—the ocean and a distant horizon line on our right and a dense blue forest made of swaying, interlocking trees on our left.

"That's all one plant," she said, pointing. "The trees are actually branches. Similar to our quaking aspen except, I think . . . sentient."

I stared at her. She shrugged. "I haven't made a study of it. But its grandfather saved my life, once."

She sat down abruptly and hauled the metal box between her legs. After a moment's hesitation, I sat beside her. A few yards away, a fist-sized green and white ball leaped from the ground and rolled down the hill. Halfway to the tall grass, ten wings popped from its unfolding carapace and it flew away, straight into the forest. Automatically, I tried to catalogue it in my mind: kingdom, animalia; phylum, arthropoda—but how absurd. It was an utter unknown. And, given the timescales involved, unknowable.

"They're going to kill me, aren't they?" she said, her voice so utterly bland that I was shocked back into attention.

I opened my mouth to deny it, but she regarded me with such a steady, piercing calm that I couldn't.

A retirement home. India. How thoughtful.

I could admit whatever I wanted out here. Even the agency couldn't touch me in another universe. So I said, "They might not, but I think . . . they won't take that chance."

The twist of her lips was bitter. "I liked the other corrupt administration better. Less imagination. I suppose they've finally realized the potential of my sandbox. Won't do to keep around a loose cannon who knows too much, right?"

We were silent for nearly a minute. The smell of anisette was more redolent up here, with overtones of copper and earth. Every few seconds a multi-harmonic buzzing, like cicadas in a trombone, pierced the air.

"I've given them something terrible, haven't I?" she said, her voice barely audible over the natural symphony. "Another planet to destroy." She laughed, a little wildly. "But it was inevitable. We're the ultimate invasive species."

Unthinking, I covered her left hand—the one missing two fingers from those five lost years—with my own. "I've worked out a few of the classification codes," I said. "They're giving access to Defense Development."

She nodded. "Weapons. Of course. Keep a few scientists here for fifty years, see what they come up with. Biological, nuclear, who cares? Instantaneous escalation." She looked down at her box. "I guess it's time."

Wearily, as though she could hardly stand to lift her arms, she typed a code into the tiny touchpad. The top of the box slid backwards. About ten of the giant paramecia floated out. They hovered around Dr. Roya for a moment, as if confused, but a wind blew and scattered them like spores. Far away from us, forever.

"How quickly do they reproduce?"

"One division a day."

It wasn't hard to calculate. "They could take over everything. In a million years this could be a giant single-cell monoculture."

"Or they could evolve natural predators," she said, mildly.

"But still, that could make the environment toxic to everything. . . ." I trailed off. Her gaze was slightly amused, but mostly sad. I could only imagine, suddenly, what that act must have cost her. "Of course," I said. "I apologize."

She held my gaze for too long, grabbing my hand when I tried to look away. As though she were weighing my soul, or grading my suitability. I had the uncomfortable feeling that I'd come up wanting on both counts.

"You've spent your entire life being sorry, haven't you?" she said, and kissed me.

I wondered what it must have been like a hundred thousand years ago for our ancestors, fulfilling their biological imperative—full of purpose, free of cultural meaning. Was copulation better than sex? Could we, homo sapiens sapiens, find our way back to that Hobbesian vacuum, even on another world?

I named the parts of her body as I kissed them: clavicle, scapula, sternum, manubrium. Her breath came in sharp jolts, as though she could only exhale when I forced the air from her lungs. A small, purple insect crawled across her nose. I laughed and brushed it off. My hand shook.

"No," she said, even as she groaned, even as I reached for the waistband of her pants. "One last time. . . . " She caressed my hair. "But it would matter too much to you."

I opened my eyes, but I couldn't look at her.

We walked toward the ocean. I squinted into the sun, an excuse for watery eyes.

"Are you a dualist?" she asked, pulling her foot from a sinkhole.

I was surprised, and then realized that I would always be surprised with her. "You're very direct."

She shrugged. "You seem like the type. God is just a means to an end."

She used her stick to tap one of the hillocks of blue filaments. Nothing happened. She tapped it again. Suddenly it popped up, like a cork from a champagne bottle. It landed five feet away. In the now-vacant mud, a miniaturized version of the lip-creature on her lab wall smacked at the empty air. Its skin was a translucent purple-red, reminding me of her.

I thought I heard her sob. But when I turned, she was smiling: an expression as close to pure joy as any I'd seen. "Adaptation," she said. "Better than heaven."

We watched it roll around before using its disproportionately large lips to burrow into the mud. After a few seconds, it disappeared completely.

"And your bosses never even believed me, Mr.—" I had winced in anticipation, but she paused. "You really hate that. You want me to think you're different." She shook her head. "It's been a long time since my opinion mattered that much to anyone. To my self-appointed executioner, no less."

She kept walking. I stumbled behind, wishing I could think of something to say that didn't involve admiration so deep and desperate it was indistinguishable from love.

"If you could live in a universe with an afterlife but without God," she said, minutes later, "or in a universe in which God exists, but you lack an immortal soul, which would you choose?"

Oxaloacetate, Citrate, cis-Aconitate. "I'm not sure."

We were closer to the ocean, now. I could hear the waves. She glanced over her shoulder; just a flash, but I withered under her contempt. "Come on."

"A soul," I said, God forgive me.

"What was your thesis?"

"Evidence for extra-solar seeding of RNA-like polymers in clay-catalyzing scenarios." The old words came so easily I forgot for a moment that I hadn't said them aloud in over ten years.

She laughed. "Panspermia and abiogenesis. You really were looking for God." She paused. "But you never finished your degree, did you?" Her gaze was nearly muscular, so efficiently did it pry open my past. "You abandoned your career. Dualism, souls . . . you loved biology, you just couldn't stand its implications."

"Science can't disprove God," I said, and winced. My professors had tried to rescue me with examples of religious scientists—Ken Miller and Isaac Newton trussed up like wax dolls in a traveling history exhibit. The Pope himself declared no conflict between Christianity and evolution. But what sort of God designs a wasp that can only gestate through the existential suffering of a caterpillar? Why would He create and destroy a billion billion species, only to save cockroaches and humans?

Her smile was disdainful. "Of course it can't. You just managed to find the one job where you wouldn't have to prove anything."

My shopworn apologetics fell away. She was right—the agency merely demanded knowledge, never conviction.

I remembered nights in the college chapel, nearly crying with the weight of those millions of dead species, 99% of all creatures once alive on the earth. What was dualism—the disembodied spirit, the earth-bound brain—to that? A flyswatter of justification in a roomful of flies. I left the church, I left the school. But I was haunted by secular ghosts, by the cruelty of Darwin's Ichneumonidae.

I had expected the ocean to be the same comic-book blue as the plants, but it was silver, like the reflected sky. We stood on a spongy ridge made from thousands of decaying blue hillocks and watched the sun set over the ocean. The sky filled with reds and purples so violent it looked as though the sun was bleeding. In the water, two giant bipedal sea-monsters called to each other in voices like submerged foghorns. They were at least a mile away from us, but when they began crashing against each other, the spray misted our clothes. I licked the water from my hand: less salty than our oceans, and distinctly metallic. I could get used to this, I thought.

Sometimes I wonder what would have happened if I had said it aloud.

"You should go back," Dr. Roya said.

I already understood that she would stay here. And that it would hardly matter to the agency if she died of old age in another universe, or from a morphine drip in India. But I hadn't anticipated that she would want me to leave.

"There's an alarm," she said. "It alerts the building if I'm gone longer than five days."

"Then we have five days," I said, like some foolish Shakespearean hero.

She shook her head. "They'll see how long you were gone. They might check the Well too early."

And if they did, they might not give her final, desperate experiment a chance to work. I had to leave so she could destroy the world.

In the end, it was easy enough. Another hole in my heart, another wall. I had spent years inured to disappointment. In many ways, it was my only real expertise. She walked me back to the gate.

"It's okay," she said. I think I was crying. "I'll be okay. I gave birth to this world. It should have my body."

My professors had all been shocked when I abandoned my doctorate. I tried to explain why, tried to convey my crisis of insupportable contradictions within a rational philosophical framework, but it came out garbled and terrified. "Catholic guilt?" one had hazarded. "No," I said, remembering childhood lessons of souls impaled in hell. "Catholic doubt."

If there was a heaven, Constance Roya would have nothing to do with it. She would be in Dante's first ring, with Aristotle and Carl Sagan, discussing underworld politics and whether demons have Hox genes.

But there wasn't a heaven.

The airlock would open automatically when I came back alone, she assured me. "Count to thirty," she whispered, her dark lips brushing against my ear. Her voice was rough, and sometimes I imagine that she was crying, also. "Then I'll be gone."

Back through the rabbit hole, out the other side.

I last saw her kneeling in the mud, one hand in her tangled hair, mouth open. As though she would scream, or say that she was glad I had come, that whatever she felt for me, it wasn't just pity.

Thirty seconds. I counted thirty-five to be sure, lying on the carpet of her lab. Her sunlight on my face, anisette in my hair.