A gang of thugs have had enough of Boston Blackie, and decide to pull out their secret weapon to use against him. The not so bright crooks on the street mistake another man for the real Boston Blackie, and anthony the fake Blackie tells the real blackie about the incident, and offers a clue involving phoney oil stock.
When Blacki responds to investigate the printing house of the phoney stocks, he falls into the hands of the blonde bomshell, a temptress who is both beautiful and smart. Meanwhile the worried Mary goes to Farraday for help.
A thug named Homer lends Blackie a hand in getting loose from his bonds. The attempt seems to only serve to show how ruthless that Olivia, the lady gangster, can be in her intentions. Though he stays tied up, Blackie tries to pick Olivia’s brain for clues.
Both Farraday and Mary are doing their own investigating to try to locate blackie. But are they gaining any ground? Farraday seems to have reached a blank wall, but Mary drives with Dalton, the fake Blackie to move in on the mobsters. Soon the gangsters have the upperhand and just when it looks worst for Boston Blackie and Mary, he manages to use a weakness of the mob boss to work against him for a dramatic escape.