At 57, George is settling down to a comfortable retirement, building a shed in his garden, reading historical novels, listening to a bit of light jazz. Then Katie, his tempestuous daughter, announces that she is getting remarried, to Ray. Her family is not pleased, as her brother Jamie observes, Ray has 'strangler's hands'. Katie can't decide if she loves Ray, or loves the wonderful way he has with her son Jacob, and her mother Jean is a bit put out by all the planning and arguing the wedding has occasioned, which get in the way of her quite fulfilling late-life affair with one of her husband's former colleagues. And the tidy and pleasant life Jamie has created crumbles when he fails to invite his lover, Tony, to the dreaded nuptials. Unnoticed in the uproar, George discovers a sinister lesion on his hip, and quietly begins to lose his mind.

The way these damaged people fall apart, and come together, as a family is the true subject of Mark Haddon's disturbing yet very funny portrait of a dignified man trying to go insane politely.