After Midnight with Boston Blackie

When Diamond Ed Barnaby is paroled from prison after serving a sentence for stealing diamonds, his fellow gang members, Joe Herschel, Sammy Walsh and Marty Beck, spring into action to reclaim the jewels. Anticipating trouble from Herschel and his gang, Diamond Ed tells his daughter Betty that he must leave town but will meet her at the Arcade Building on Friday. After retrieving the gems, Diamond Ed locks them in a safe deposit box at the Arcade Building, intending to give them to Betty. Several days later, a porter with a telegram for reformed jewel thief Boston Blackie pages him on a train. Inspector Farraday, Blackie's nemesis, who is also a passenger on the train, identifies himself as Blackie and accepts the telegram. It is from Betty, asking Blackie, her father's friend, to meet her at the train station. Claiming that he has made a mistake, Farraday returns the telegram to the porter, who then delivers it to Blackie. At the depot, Betty tells Blackie that her father is missing, and he invites her to join him and his sidekick The Runt on a cab ride to the mansion of his eccentric millionaire friend, Arthur Manleder, where Runt plans to marry dancer Dixie Rose Blossom. When Blackie realizes that Farraday's assistant, Sergeant Mathews, is trailing them, he tricks Mathews by leaving the mansion through the back door with Runt, thus delaying the wedding. As Blackie proceeds to the Arcade building, Herschel and his thugs interrogate Diamond Ed at the Flamingo Club and force him to disclose the location of the diamonds. After Herschel and the others leave the office, Diamond Ed, who is tied up, knocks the phone off its receiver and dials Farraday's office. As he speaks the words "two men at the Arcade Building," a shot rings out and the line goes dead. Farraday and Mathews rush to the building, and when Blackie and Runt appear, the inspector arrests them for murdering Diamond Ed to gain possession of the diamonds. Blackie convinces Farraday to release Runt so that he can get married, and Runt returns to the Manleder house. Farraday then takes Blackie to headquarters for questioning, but when the inspector accidentally knocks over a lantern and starts a fire, Blackie escapes. When he arrives at Manleder's, Blackie discovers Manleder, Runt and Dixie locked in a closet and a note from Herschel's thugs demanding the diamonds in exchange for Betty. After Runt steals Dixie's fake diamond brooch, he and Blackie drive to the Flamingo Club with Manleder. When they arrive at the club, Farraday is waiting at the front door, and so Blackie sneaks in the back, carrying the fake stones, which he plucked from the brooch. In his office, Herschel, who has stolen the diamonds from Diamond Ed's box, negotiates their sale with a fence. When the man's offer is too low, Herschel locks the gems in his safe. Watching Herschel from the hallway, Blackie waits until he leaves the office, then unlocks the safe and removes the diamonds. When Walsh and Beck enter the office, Blackie drops the jewels in a pitcher of water and then offers to trade the fake diamonds for Betty. When Herschel interrupts their transaction and recognizes the gems as fakes, Blackie grabs Betty, locks Herschel and his thugs in the office and climbs onto the roof. From there he signals Runt, who is waiting on the street below with Manleder. Runt climbs onto the roof with a ladder and helps Betty down just as Herschel, who has discovered that the diamonds are missing from his safe, breaks down the office door and rushes to the rooftop. Herschel and his thugs seize Blackie just as an air raid warning sounds, plunging the city into blackness. Disappearing into the darkness, Blackie jumps on a ledge. Runt then recruits Farraday and Mathews to help hold a canvas tarp so that Blackie can jump to safety. After successfully jumping from the roof, Blackie throws the canvas over Farraday and Mathews and hides in the club's basement with Manleder, Betty and Runt. There, Blackie instructs Runt to take Betty to safety, and after they leave, Herschel and his thugs come charging down the stairs. After subduing the gang, Blackie and Manleder climb back to the street and are greeted by Farraday. Refusing to believe Blackie's claim that the diamonds are in Herschel's office, Farraday arrests Blackie. Manleder quickly trades places with him, however, and when Farraday finally realizes his mistake upon returning to police headquarters, Manleder tells him that Blackie has returned to the Flamingo Club. As Farraday drives back to the club, Blackie watches as Walsh shoots Herschel for double- crossing him. Blackie then enters the office and, after calmly pouring himself a glass of water, drinks it, spitting the diamonds into his handkerchief. Blackie is in the process of offering Walsh the diamonds in exchange for Diamond Ed's body when the sound of approaching police sirens sends them running down the back stairs and into the street, where they steal Farraday's car. After switching on the radio transmitter so that headquarters will overhear their conversation, Blackie tricks Walsh into admitting that he shot Herschel and that Diamond Ed's body is hidden in the trunk of Farraday's car. Blackie then broadcasts his destination over the radio, and when Walsh hears the sound of sirens, he turns on the radio and realizes that Blackie has double-crossed him. As Walsh and Blackie fight, the car crashes into a building and Blackie subdues Walsh just as the police arrive. Back at the Manleder house, Runt is about to say "I do" when Farraday arrives with a warrant for Dixie's arrest for bigamy.