In a hotel room, Helen Lloyd watches as thief Morris Lavalle places her sister Marie's pearl necklace in a shoe. Helen pulls a gun on Morris, but he escapes when the police knock on the door. Marie's husband is police commissioner John Hartley, and Helen is able to leave without explaining why she is in Morris' hotel room. The police confisicate the trunk that holds the shoe containing the necklace and it is taken to a police auction. Once the trunk is purchased, Helen breaks into the new owner's home and finds Dick Manning, a detective pusuing Morris and his gang, also trying to get the necklace. Then, three gangsters enter, and as Helen hides behind a door, Dick convinces them that he is a thief, and they agree to share the profits from the trunk with him. Once Dick removes the necklace, however, the gangsters beat him up and take the necklace to Morris, who discovers that it is a paste copy. Marie and John's anniversary is the next day, and so that her mother-in-law will not suspect Marie of infidelity, Dick promises to retrieve the necklace without filing a police report. John gives Dick the real pearls to use on Morris as bait, and then Eddie, one of Morris' henchmen, arrives to take Dick to meet Morris. On the way to the meeting, Eddie stops at the Baker warehouse, and he and his fellow gangsters force Dick to crack a safe. Dick activates the alarm and tries to stall until the police arrive. The police arrive too late, and Eddie loses them after a chase. At the gang's hideout, after Dick signals the police, he throws the pearls at Morris, and a struggle ensues. Dick regains the necklace and leads the gangsters in a rooftop race. After the police arrive, Dick speeds to the Hartley anniversary party and gives the necklace to Marie in time for her to show it off as she greets her guests. Dick then joins Helen at the party.