In the Christmas spirit, Boston Blackie decides to entertain the inmates at his old "alma mater" by bringing a variety show headed by clown Roggi McKay. Roggi drops one of his showgirls, Eve Sanders, as she has already visited her prisoner brother, Joe Trilby, the maximum allowed number of times that month. However, Blackie kindheartedly lets her tag along.
Inspector Farraday and Detective Joe Mathews unexpectedly join the group on the bus, just to keep an eye on Blackie. When Joe manages to escape from the prison, by tying Roggi up and putting on his costume and makeup, Farraday suspects Blackie helped him.
Blackie heads to Eve's apartment. Sure enough, Joe shows up soon afterward. Joe claims he is innocent and that Duke Banton and someone named Steve got him to drive them to the crime scene without telling him why. When the robbery was foiled, they fled, leaving him behind. Now he wants to kill the pair, regardless of the consequences. Joe takes Blackie's suit and ties him up. Eve eventually arrives and frees him.
Blackie and his sidekick "the Runt" head to Duke Banton's place, but arrive too late and find only a dead body. Then Joe enters. He claims he did not kill Banton. When the police surround the building, Blackie has Joe switch places with Banton after Farraday has examined the corpse. The "body" is taken away in an ambulance. Blackie is taken into custody, but manages to victimize Detective Mathews, putting on his uniform to get away.
From information provided by Jumbo Madigan, Blackie figures out that the other robber was taxi driver Steve Caveroni. He has Eve pose as a fare to lure Caveroni to Banton's hotel room. Caveroni feels he is in control of the situation as he has a gun, so Blackie has little trouble getting him to confess he killed his partner (Banton was trying to flee, leaving Caveroni to take the blame) and that Joe is innocent. Farraday and his policemen eavesdrop through the door. Once he realizes he is trapped, Caveroni makes a break for it, but is shot dead.
