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.

Deep in the jungle, unscrupulous Black John, a descendant of pirates, conducts an ancient ceremony to harm Tarzan and his apes. Among Black John's tribe of superstitious followers, castaway Mary has caught his eye, and as a result, the hideous leader is bent on making her his bride. However, Tarzan has already seen beautiful Mary bathing in a calm forest pool and will stop at nothing to protect her. Now, Black John is hell-bent on taking Tarzan out of the way, and establish himself as the Earl of Greystoke. But, can he defeat Tarzan the mighty?—Nick Riganas