Dominic Birdsey's identical twin, Thomas, is paranoid schizophrenic. With proper medication he can work at a coffee stand, but occasionally he has severe outbreaks. Thinking he is making a sacrificial protest that will stop the war in the Middle East, Thomas cuts off his own hand in a public library. Dominic sees him through the ensuing decision not to attempt to reattach the hand, and makes efforts on his behalf to free him from what he knows to be an inadequate and depressing hospital for the dangerous mentally ill.

In the process, Dominic reviews his own difficult life as Thomas's normal brother, his marriage to his ex-wife which ended after their only child died of SIDS (Sudden Infant Death Syndrome), and his ongoing hostility to his stepfather. First in Thomas's interests, and then for his own sake, he sees a gifted Indian woman employed by the hospital as therapist. She helps Dominic come to understand Thomas's illness and the family's accommodations or reactions to it in terms of the whole family system.

In the course of treatment, Dominic discovers sexual abuses taking place in the hospital and helps to expose the perpetrators. He succeeds in getting Thomas released, but Thomas soon commits suicide. After Thomas's death Dominic finds out about their birth father--a secret their mother had shared with Thomas, but not with him.

He also learns that the woman he has been seeing is HIV-positive. She asks him to keep her baby if she dies. At first he resists, but later, having found his way back into relationship with his wife, he takes the baby. The book ends with several healing events that leave Dominic able to cope with the considerable loss, failure, and sadness in his personal and family history.