The Unnamed, By Joshua Ferris

The exceptional Then We Came to the End – a snappy, witty dissection of office life – won Joshua Ferris the PEN/Hemingway Award in 2008 for the best debut novel by an American author. Its biting depiction of the paranoia that accompanies a round of redundancies marked him out as a writer perfectly in tune with the Zeitgeist.

Which means that expectations for his follow-up are understandably, but perhaps unfairly, mountainous. It also means that anyone expecting more of the same will be sorely disappointed: The Unnamed is more Cormac (McCarthy) than Coupland (Douglas): distressingly bleak rather than distastefully blithe; staccato-sentenced rather than sardonically satirical.

Tim Farnsworth is a high-powered New York lawyer. He has a wife, Jane, who is an estate agent, and a teenage daughter, Becka, who is distant and a typical pain. He also has a condition: at inopportune moments (though it's hard to think of any opportune ones), he can't stop his legs from walking. It might be a psychological condition – all the specialist medical practitioners he sees seem to think so. It might be physical – though quite how, no one knows. It is, simply, "Unnamed". And, as he tells his wife at the end of the first chapter, after four years dormant, "It's back."

At first reading, it seems a mildly amusing affliction: "He had been forced out of the building and into the street. At 43rd and Broadway he hailed a cab, which he hoped would take him back to the office. After getting the cab to pull over, he reached out and opened the back door. But then he walked on. The driver, a Sikh in a pink turban, honked the horn, staring at him through the rearview mirror. Why would someone hail a cab and open the door only to keep walking?"

But the condition is clearly serious. In some distress at his marching legs, Tim tries to call an ambulance to help him, only to slip on a patch of ice and let go of his phone while trying to steady himself. Anyone else would obviously stop to pick it up. But Tim? "'My phone!' he cried out as he regained his balance. 'Somebody! My phone!' He walked on with a tweaked back. 'Please get my phone!' Everyone ignored him. His BlackBerry had landed in the middle of the street where it lay defenseless against oncoming cars. He kept moving forward."

If the gravity of his situation were in any doubt – if readers still expected Ferris to turn this on its head and deliver a droll rejoinder along the lines that we all think we're walking aimlessly in life – then an early scene puts that to rest quickly enough. What will he do, asks Jane, if the condition really is back? "I will buy a gun," he says, "and blow my head off."

So begins a story of a family on the edge. Jane constantly has to look after Tim – strapping him down at night and going on long drives to find him when he inevitably disappears – which leaves Tim feeling guilty that he is such a burden, and Jane feeling guilty that she sometimes entertains thoughts of leaving him. As for Becka, she is going through a phase of teenage rebellion that doesn't really fit with having an absent father with an odd quirk. Jane contemplates an affair, and feels even guiltier; Tim realises he doesn't want to go back ' home once he's walked away – and he feels guiltier. Getting the gist?

But even this feeling-at-faultfest cannot compensate for the one major flaw with this novel: Ferris's protagonists are little more than ciphers. It's just about possible to feel bad for them – particularly Tim, who towards the end has not only lost his wife and his career but also his extremities, courtesy of the frostbite that accompany the transient's life – but beyond knowing about their jobs (or, in Becka's case, her disappointments), there is little said about their characters other than in relation to the walking curse.

This inevitably means that Tim's predicament is front and central – and if it is to take up that position, surely it needs to have meaning, to tell us something about the modern condition? But searching for that meaning is as fruitless as Tim's attempts to comprehend his problem. "He had lost his way somewhere," Ferris writes. "He had forgotten why he had pushed and pushed to come so far."

The same could be said of the reader, who might be forgiven for wondering why it is they have just read 300-plus pages – unless they enjoy a good existential disquisition on despair, of course.