"Saturday, February 15, 2003. Henry Perowne is a contented man, a successful neurosurgeon, the devoted husband of Rosalind and the proud father of two grown-up children, one a promising poet, the other a talented blues musician. Unusually, he wakes before dawn, drawn to the window of his bedroom and filled with a growing unease. What troubles him as he looks out at the night sky is the state of the world, the impending war against Iraq, a gathering pessimism since 9/11 and a fear that his city, its openness and diversity, and his happy family life are under threat.
Later, Perowne makes his way to his weekly squash game through London streets filled with hundreds of thousands of anti-war protestors. A minor car accident brings him into a confrontation with Baxter, a fidgety, aggressive young man, on the edge of violence. To Perowne's professional eye, there appears to be something profoundly wrong with him.
Towards the end of a day rich in incident, a Saturday filled with thoughts of war and poetry, of music, mortality and love, Baxter appears at the Perowne home during a family reunion, with extraordinary consequences."