They call her the P.I. Princess. In 1947 Allie Fortune is the only female private investigator in New York City, but she's kept awake at night by a mystery of her own: her fiancé disappeared in the war, and no one knows if he's dead or alive. Until Allie finds out, she will have no peace. When there's a knock on her office door at four in the morning, Allie suspects trouble as usual, and Mary Gordon is no exception. Mary claims someone is following her, that her apartment has been ransacked, and that she's been shot at, but she has no idea why any of this is happening. Allie takes the case, and in the process discovers an international mystery that puts her own life in danger.

The FBI is working the case as well, and Allie has been partnered up with an attractive, single agent who would be perfect for her under other circumstances - if only she knew whether her fiancé was alive.