Lila Black is holidaying in Hell—or, more properly, Daemonia. Her last mission is completed; she is newly married to her lover, the elf Zal and to the demon Teazle; and she has achieved a considerable level of status in her current residence. In the malleable, playful, complex world of Daemonian society, her mental and physical modifications are less remarkable and the constant duelling required to maintain her place in the hierarchy provides a convenient—even pleasurable—outlet for her violent instincts. But her employers aren't intending to allow her to relax for long, and nor are the demons who surround her. It seems like whenever she starts to believe she's finally in control of her life, someone or something pops up to contradict her. Her home plane of Otopia is suffering a plague of Mothkin, inimical parasitic fae creatures. The Agency wants to send her to Faery. Daemonia holds its own dangers both for her and for her friends and associates. And Lila isn't sure she knows what she wants or how to get it.

Going Under, the third volume of Robson's Quantum Gravity series, is at once darker and more open than the first two (Keeping It Real [2006] and Selling Out [2007]). Umeval, the level of Faery in which Lila finds herself is both bleaker and more alien than she—or the reader—would expect, a place not of courts and bargains, nor of lush landscapes and natural powers, but a raw, visceral chaos where nothing and no one is stable or safe. "The mountain there... it has a horribly familiar cast to it, like the gleam in a little old lady's glass eye just before she trips you up and shoves you in the oven. Let's go the other way" (p. 171). This is the stuff not of fairytale, but of primaeval nightmare, inhabited by creatures drawn from the grimmest parts of the mind and where familiar forms are warped, questioned, stripped away. "The lassie doesn't like to know what she knows," says the Imp Thingmajig early in the book (p. 33); he's speaking of Lila, but as the pages turn it becomes clear he could as well be speaking of the reader.

The world-building, as ever with Robson, is convincing and disturbing in real measures as things both Lila and the reader believe themselves to know are stripped back and refined. The delicate beauty of the fae Viridiana and Poppy—already questioned in Keeping It Real—is stripped away to reveal the authentic and brutal meaning encoded in their legend (they are water-horses). Teazle sports wings that remind us of the Angelic fall that underlies the existence of demons. Word on word, Robson restores to us the treacherous and violent Faery of our distant ancestors.

At the heart of all this is Lila herself, still questioning, still challenging, still stubbornly and sometimes viciously insecure. She's still looking for a more magical connection to the worlds around her, still trying to bind herself closer to Zal and failing, still chasing after the security and love that her family denied her, still locked into the belief that his every pain is her fault. Her part-human body still evades and frustrates, not wholly her own, not wholly comprehensible or controllable, all too vulnerable, it seems, to the whims and expectations of others. "Everything feels like manipulation now" (p. 191). Her rebuilt form makes explicit the constraints of being female: having no choice but to inhabit a shape that is socially decreed to be a form of public property, liable to the judgement and manipulation of others at every turn. Lila's body may be partly machine but its bafflingness, its vulnerability to the demands of others, and her lack of full ownership will be familiar to many female readers. She is trammelled on every side by the expectations of those around her, locked into patterns of behaviour laid out and approved for her by others, and perpetually conflicted. She isn't nice and she doesn't always get what she wants. She's resentful and angry and suppliant and powerful and weak all at once. In a genre currently top-heavy with kick-ass, pseudo-damaged, tough-girl protagonists, Lila Black is an authentic voice. Robson is neither sentimental nor self-indulgent and her depiction of her heroine is clear-eyed. She doesn't require us to like Lila or admire her. But—to this female reviewer at least—this series is the best feminist SF in years.

Going Under also serves to open out our understanding of some of the other characters, notably Malachi, the Agency's Fae operative. Rather more of the story than in the preceding two books is told from viewpoints other than Lila's, which permits Robson to bring more aspects of the over-plot to the fore, providing some useful clarity as to the complex politics of her worlds. The writing is crisp and sharp, sometimes beautiful ("Madrigal was waiting for them, a small dark shape hunched over a tiny fire, her guns sticking up at her back like wayward posts in a fallen scarecrow" [p. 199]), sometimes delightfully, unexpectedly funny ("A sparkle of bright lime scattered between them. It got up Zal's nose and he sneezed. Lila laughed, and the city, and Moguskul, looked up" [p. 198]). The pacing is solid: duels and ambushes in Daemonia are counterpointed by thoughtful explorations of the nature of the worlds and of Lila herself. The journey into Umeval is thick with atmosphere and foreboding. It is a very good book, although I have one or two reservations. It takes nearly two thirds of its length for the protagonist to arrive in Umeval; I would have liked to have spent longer there and perhaps a little less time on the ins-and-outs of Lila's relationship with the Agency (and my best friend is very clear that she would liked to have seen the full panoply of a wedding in Hell). The set pieces are terrific, not least the airborne expedition into the wilds of Daemonia, but there is also a suddenness to some of them that can be startling and disquieting—as, I suspect, Robson intended. But I insist on mourning certain characters whose lives are cut brutally short. The final twist in the tale felt a little unfair: I was not yet quite done with things as they were. But the progression of the series so far encourages me to have faith. We are in good hands with Justina Robson, and I will be awaiting volume four with impatience.

Kari Sperring is the author of Living with Ghosts, due from DAW books in March, and is the reviews editor for Vector, the critical journal of the British Science Fiction Association. As Kari Maund, she is an historian of Britain in the early middle ages and has published five books and many articles in that field. With Phil Nanson, she is co-author of The Four Musketeers: the True Story of d'Artagnan, Porthos, Aramis and Athos. She lives and works in Cambridge, England.