A racketeer who is recently released from prison draws the attention of Boston Blackie. The racketeer is back to his old tricks of stealing cars, but when Blackie tries to warn Lt. Farraday the advice falls on deaf ears. Between the Commissioner, and Blackie, the cops wake up to trying some preventive measures to stop criminal behavior from spreading among the youth of the city. It takes a murder to get the evidence the cops need to pin on the bad guy, and stop his influence on making more juvenile delinquents. Blackie works his own sting operation to get the goods that the cops need.