Six days ago, a man blew himself up by the side of a road in northern Wisconsin. The explosion that detonates the narrative of Paul Auster's remarkable novel also ends the life of its hero, Benjamin Sachs, and brings two FBI agents to the home of one of Sachs's oldest friends, the writer Peter Aaron. What follows is Aaron's story, an intricate, subtle and gripping investigation of another man's life in all its richness and complexity.