Harry Houdini as Quintin Locke, a secret service agent battling an international conspiracy to block any sort of scientific progress. Among the villains are the vicious DeLuxe Dora, the "Madagascar Strangler", and a strange robot named "Q". Marguerite Marsh, the older sister of silent movie star Mae Marsh, played the heroine. Of course, each installment of the serial ended with a cliffhanger in which Houdini had to use his famous escape artist skills. The series was very popular with the public.