The hero of Joshua Ferris’s new book is Tim, a high-powered New York lawyer in late middle age who suffers from a rare and upsetting ailment. Every now and again, his legs decide to take him for a walk whether he likes it or not. One moment he’s buttering a slice of toast, or chairing a meeting with a client, and the next he’s up and off, travelling who knows where in whatever the weather. Hours later, his legs aching with exhaustion, he finds himself back in control – and collapses irresistibly into sleep wherever he may be.

This is not so amusing as it sounds. His walks strand him in the outer reaches of the city, and when the weather is bad put him in danger of freezing to death. When such episodes loom, his wife Jane dresses him up in all-weather gear and affixes