When "Diamond" Ed Barnaby (Walter Baldwin, uncredited) is paroled, he plans to give his daughter Betty (Ann Savage) $100,000 worth of diamonds. Aware that dangerous people are watching him, he hides the jewels in a safe deposit box. After Betty is called to meet her father and he never appears, she turns to Horatio "Boston Blackie" Black (Chester Morris) for help. Blackie takes her to the safety of his wealthy friend Arthur Manleder's (Lloyd Corrigan) apartment while he investigates. Meanwhile, crooks led by Joe Herschel (Cy Kendall) force Barnaby to reveal the location of the diamonds. Barnaby tries to call the police, but is killed before they arrive. Inspector Farraday (Richard Lane) and Sergeant Mathews (Walter Sande, uncredited) respond and, suspecting Blackie, arrest him just as he is about to open the (now empty) deposit box. After escaping, Blackie finds Betty has been kidnapped, with a ransom demand for the diamonds. Using fake gems, he heads to the Flamingo Club, infiltrates Herschel's office, and cleverly recovers the real jewels. Swapping the fakes for Betty's freedom, Blackie faces further complications as Herschel is exposed and killed by an associate, and the real diamonds’ fate hangs in the balance. Blackie ultimately outsmarts the gang, engineering a confession with the help of the police, and ensures justice is served. In a comic subplot, Blackie's sidekick the Runt's (George E. Stone) wedding to Dixy Rose Blossom is repeatedly disrupted, ending with Dixy's arrest for bigamy. Cast: - Chester Morris as Boston Blackie - Richard Lane as Inspector Farraday - Ann Savage as Betty Barnaby - George E. Stone as The Runt - Lloyd Corrigan as Arthur Manleder Runtime: 65 minutes.