The Unnamed, By Joshua Ferris

Joshua Ferris's debut novel was written in the first-person plural. The narrative voice in his second, in contrast, could hardly be more singular. The Unnamed follows Tim Farnsworth, a lawyer who loves his job and his conventional family life as fiercely as the collective copywriters of Then We Came to the End's ad agency disdained theirs.

His meticulously constructed existence is thrown into chaos by a medical condition that nobody can explain. At any moment, for no reason at all, he is liable to find that his legs are wheeling under him, that he is being taken on an involuntary walk as likely to end up at a clifftop as a crossroads, without regard for his safety or the demands of his job or the worries of his loved ones. "Benign idiopathic perambulation", one doctor calls it, but the condition is anything but benign.

With this unsettling premise, Ferris stakes out his own claim on territory that has been occupied many times before, from King Lear to The Road: unaccommodated man, shorn of his palliative trinkets, and forced to face the terror of the void. After the office politics of his debut, it's a grand purpose, and consciously so. This time, Ferris said in a recent interview, the idea is "to get the fiction closer to the essential questions".

In a sense, this underplays his previous achievement. Then We Came to the End is a marvellous novel, and its purpose is not as slight as its comedic manner suggests. Indeed, it is not totally alien from the work going on here, sharing a prodding fascination in the tension between our social and selfish selves, in what remains when we are faced with losing what The Unnamed calls our "steadfast convictions cradled in a swivel chair".

Moreover, in that collective narrator, Ferris had a structuring device that made his subject soar, and that that perfectly matched the tentative collaboration of office life – and its attendant identity crises whenever the group grew or diminished.

Accomplished though it is, quartz perfection though its sentences are, the story of Tim Farnsworth never quite reaches the same heights. I suspect that this is in large part to do with its own controlling conceit. A man who seems fated to walk in the wilds for the rest of his days is not without a certain mythic resonance - the correspondences to Lear, in particular, are marked - but he is also an alien.

Poor Tim is stuck in circumstances that can never quite translate to our own experience, and the result is that his abrupt hikes rarely transcend their obviously allegorical purpose.

This effect is only increased when the relapsing-remitting condition makes its final return, forcing Tim from the loving arms of his wife Jane and out onto the blasted heath. As our hero's mental state seems to disintegrate, his attention hones in on the battle, as he perceives it, between his body and soul. Soon that terrible Other, his physical self, is asserting itself conversationally as well as practically.

Above all, it sneers at his late religiosity. "If I can make you forget words, make you flatline, make you see things and seize up," his wandering body asks, "is that not all the evidence you need that I control your fate, and that my fate is your only future?"

Sometimes, as when Tim doggedly forces his treacherous body in the direction of his daughter's blossoming family, this debate is tremendously affecting, and it grapples with one of the "essential questions" for which Ferris has set his course. The problem is that it is also placed in a weird novelistic limbo. Until this section, the book has had the helpful narrative anchors of work and home life to keep it from floating away; now all we have are Tim's wavering internal duologue and the great beyond. With internally logical but mutually uncommunicative sentences, presumably intended as the product of a dissociating consciousness, almost any paragraph could be moved ten or 20 pages forwards or back without making any great disturbances to the texture.

Apt this may be; compelling it is not, conjuring only the spectre of some relentless bar-room bore, who may very well be getting at something profound, but cannot quite dredge up the specifics to bring it from his realm into yours. In the end, Tim manages a kind of clarity, and the book's final pages are undoubtedly moving; also, you will have raced through the rest of the book to reach them. It is only a pity that, even at the last, our response is qualified by the fact that this tragic figure's fate cannot quite be forced to square with our own.