Broadway gambler "Gloves" Donahue (Humphrey Bogart) wants to find who killed the baker of his favorite cheesecake. He sees nightclub singer Leda Hamilton (Kaaren Verne) leaving the bakery. When her boss Marty Callahan's (Barton MacLane's) partner Joe Denning (Edward Brophy) is murdered, Leda and her accompanist Pepi (Peter Lorre) disappear. It turns out that beneath all of the mystery is a gang of Nazi operatives planning to blow up a battleship in New York harbor.