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.

A dying woman tells her son, Barry Griffith, she had been a surrogate mother for a millionaire, and that he is a twin to that baby. He seeks out his twin, Frank Bentley to get a bite of his inheritance, but he's not the first long-lost brother to call. Barry stakes out across the street from Frank's home so he can spy and release the story to a tabloid paper. In the process, he begins an affair with Frank's mistreated wife.