The sixth Tarzan film to feature actors Johnny Weissmuller and Maureen O'Sullivan. Of interest is the uncredited appearance as a circus roustabout by Elmo Lincoln who in 1918 was the VERY first actor to star as Tarzan. When Boy is taken to New York by plane, Tarzan and Jane follow. Through a nightclub entertainer and the pilot of the plane, they learn that their son is in the custody of the circus people who brought him to America. Tarzan and Jane go to the circus to claim him, but are unsuccessful. Taking court action, Jane hopes to regain custody of Boy, but on cross-examination inadvertently admits she is not the natural mother of the child, and Tarzan is restrained when he manhandles the circus men’s attorney. Jane agrees to let Tarzan follow his own instincts, and he escapes and heads for the circus, where the circus owners are planning to leave with Boy and their employees’ wages. And though they temporarily immobilize the jungle king, he is able to block them with support troops summoned from the circus elephants. Later, the court, while not condoning Tarzan’s tactics, acknowledges the genuine motive behind them, and allows the family to return to its jungle home.