Jimmie Hallet is walking through a heavy fog one night when, seemingly out of nowhere, a girl appears, shoves a bundle of papers and a slip of paper with an address on it into Jimmie's hands, then disappears. Intrigued, he goes to the address on the paper, and is promptly knocked out by a blackjack. When he wakes up the next morning he discovers the dead body of a man named Greye-Stratton and learns that the "mystery girl" was Stratton's daughter Peggy. Jimmie soon finds himself questioned by the police about her father/s murder and mixed up with a gang of thieves and killers led by a mysterious thug named Ling.