Why does the coma victim have a concentration camp number?

A Canadian estate locator is asked by a client's niece to determine the identity of a coma victim in an English hospital, where she is a nurse. The only clue is a number tattooed on his arm. The search leads to France and the identity of a woman who was deported to Auschwitz in 1944. A romance develops between the locator and the nurse. The story correspondingly follows the progress of a young Englishman who converts to Judaism and the consequences for him and his family. The novel examines attitudes toward outsiders, by those whom they wish to join, and the views of those who consider anyone who turns their back on the tribe to be a defector. The two stories connect toward the end, when the power of the various relationships is revealed.