On this particular Saturday morning, Perowne’s day moves through the ordinary to the extraordinary. After an unusual sighting in the early morning sky, he makes his way to his regular squash game with his anaesthetist, trying to avoid the hundreds of thousands of marchers filling the streets of London, protesting against the war. A minor accident in his car brings him into a confrontation with a small-time thug. To Perowne’s professional eye, something appears to be profoundly wrong with this young man, who in turn believes the surgeon has humiliated him — with savage consequences that will lead Henry Perowne to deploy all his skills to keep his family alive.