Mysterious deaths have been occurring in the same towns as Miller's Circus and the Governor has sent Ken Kenton to investigate. Ken joins the show but when he realizes that Bargoff is involved, Bargoff has fled and taken Mary Hiller as a hostage. The trail leads to Baron Petroff who concocted the deadly chemical and Ken quickly finds himself the Baron's prisoner.

Brett runs a protection racket for an unknown boss. When Jeff Hayes arrives and opens a gambling den, they try to shut him down. Unlike the others who have given in, he plans to fight back.

A cowhand named Bob Blake visits with Sally Thompson and her kid-brother, Jimmy, on their hard-scrabble homestead adjoining the Steele Ranch where Bob works. He learns that their father just died, and he plans on seeing if he can make things a bit easier for them.

Mary and Bobby Trevor are castaways befriended by Tarzan. When Lord arrives, looking for the family heir, Black John tries to fill that role and marry Mary in England. Tarzan shows up and marries her instead.

A feud between two gangs in Chinatown breaks out into a tong war.