An unknown judge invites a guilty governess and others to a 1930s safari, for justice one by one.

An adventurer (Hamilton) decides to go in search of the Lost City in the Amazon jungle. A motley crew of other people decide to join him for the wealth of the city, for reasons of their own. But to their horror they find out that they have bitten off more than they can chew, what with a Nazi doctor still using the place for his human experiments.

When his experiments into a powerful new anesthetic go hideously awry, respected physician Dr. Jekyll transforms into the hideous Jack Hyde. As his wife Elisabeth passes her time in charitable work, rehabilitating the district's fallen women, Hyde is drawn into an escalating cycle of lust and murder that seems to know no bounds.