According to her own complex moral calculations, Katie Carr has earned her affair.

She's a doctor, after all, and doctors are decent people, and on top of that, her husband David is the self-styled Angriest Man in Holloway.

When David suddenly becomes good, however - properly, maddeningly, give-away-all-his-money good - Katie's sums no longer add up, and she is forced to ask herself some very hard questions.... Nick Hornby's brilliant new novel offers a painfully funny account of modern marriage and parenthood, and asks that most difficult of questions: what does it mean to be good?