Frank Keller is a New York detective investigating a case of a serial killer who finds the victims through the lonely hearts column in newspapers. Keller falls in love with Helen, the main suspect in the case. Seen-it-all New York detective Frank Keller is unsettled - he has done twenty years on the force and could retire, and he hasn't come to terms with his wife leaving him for a colleague. Joining up with an officer from another part of town to investigate a series of murders linked by the lonely hearts columns he finds he is getting seriously and possibly dangerously involved with Helen, one of the main suspects.