The basic plot is probably familiar to fantasy fans: a unicorn, living at peace in her forest, overhears a human conversation about the fact that there are no unicorns left in the world. The unicorn, who "had never minded being alone, never seeing another unicorn" (p. 4), because she was confident that there were others like her out there, is suddenly restless. "From that first moment of doubt, there was no peace for her; from the time she first imagined leaving her forest, she could not stand in one place without wanting to be somewhere else" (p. 5).
Determined to find the rest of her kind, she sets out into a world much less tranquil and verdant than her forest. Most of the humans she meets fail to recognize her for what she is, looking at her and seeing only a white mare. She is imprisoned in a carnival cage with other mythical and extraordinary creatures, and even there, a witch must still enchant her to convince the carnival's visitors they see a unicorn.
Eventually, the unicorn escapes and acquires two companions who are on quests of their own, Schmendrick the Magician, who is trying to awaken his powers, and Molly Grue, who abandons her life as Maid Marian to a group of forest-dwelling outlaws to join Schmendrick and the unicorn. The three follow rumors of the Red Bull, who, they are told, drove the rest of the unicorns from the land years ago.
The rumors bring them to a town called Hagsgate and to the gloomy castle that overhangs it, where a king named Haggard keeps the Red Bull. To save the unicorn from the Red Bull, Schmendrick unintentionally turns her into a shining woman called the Lady Amalthea. When the three companions arrive at the castle, Lady Amalthea quickly catches the attention of Prince Lir, Haggard's adopted son, who busies himself with quests meant to win her favor and, in the process, becomes a hero. Schmendrick serves as magician to King Haggard, who has spent his life trying and failing to figure out what makes him happy, and Molly serves as cook.
Although Schmendrick, Molly, Amalthea, and Lir ultimately defeat the Red Bull and King Haggard and free the unicorns, and although the secondary characters resolve their own quests, the story's ending is not entirely happy. Amalthea resumes her unicorn form and must part from Lir. Having once been human and in love, a new sadness hangs over her even after she returns to life as a unicorn. Still, Beagle convincingly makes the point that the unicorn's journey from her forest to mortality and back again was worth all the trouble because of the humanity it gave her.
What made the book most memorable for me, however, was not the story line but the small moments of humor sprinkled throughout. I was startled into laughter by Prince Lir, explaining his heroism and his love to the Lady Amalthea: "I became a hero to serve you, and all that is like you. Also to find some way of starting a conversation" (p. 180). I was reminded of Neil Gaiman, though I suppose the comparison should go the other way around, when the magician Schmendrick sees Haggard's castle for the first time. "Its skinny spires looked nothing like a bull's horns, but rather like those on a jester's cap. Or like the horns of a dilemma, Schmendrick thought. They never have just two" (p. 107).
There are moving moments of commentary and observation, too. Toward the end of the book, as Schmendrick and Molly seek the Red Bull, a talking skull explains to them that the way to the bull is through a clock. But the path will only work if Schmendrick and Molly change their conceptions of time. "When I was alive, I believed ... that time was at least as real and solid as myself, and probably more so," the skull tells them. "I lived in a house bricked up with seconds and minutes, weekends and New Year's Days, and I never went outside until I died, because there was no other door....[But] you can strike your own time, and start the count anywhere" (p. 169). It is, Schmendrick says, the way the best magicians think of it, and the characters can only defeat the Red Bull when they start thinking that way too.
I was disappointed only by the character of Molly Grue. Like the other characters, she got something she wanted—an escape from the drudgery of her life with the outlaw Cully and his men—out of her journey with the unicorn. But other than her initial insistence on accompanying Schmendrick and the unicorn, she made few decisions in the story. She adopted the same roles of cook and comforter in Haggard's castle that she had held in the forest. She took little action in either of the battles with the Red Bull. It is only at the end, when Schmendrick asks her to come with him on the next leg of his journey, that Molly seems to make any kind of active choice.
Even so, Molly feels alive, just like the rest of the novel's characters. And this is the story's greatest virtue: that despite the dreamlike nature of the premise and setting, truth and humanity shine out of the book as brightly as any of Beagle's unicorns.