Prindle and his companions, Shepard and Quinn, come to Mexico in search of a lost Inca city which they believe holds a great treasure. Just when they are about to get on their way, an orphaned pickpocket named Paco steals their wallet containing some important film that would help them find the lost city. They begin a manhunt for him but fail to get to him after Herbie helps him escape and get aboard a cruise ship to Panama.
In Panama, Prindle and Quinn are waiting for Paco while he's being escorted off the ship but he manages to escape. He then goes to a garage, where he plans to go into business as a taxi driver and paints Herbie to reflect this. However, his business venture is threatened by Prindle, who demands him return the film, or else they will cut Herbie into scrap metal. To show that he is not bluffing, Prindle orders Quinn to light a propane blowtorch and barely not touch Herbie. Paco succeeds in getting the film back but double-crosses them. This soon leads to a chase out of Panama and into a bullring where a bull knocks their car onto its side and they lose Paco and Herbie.
They regroup with Shepard and continue their search for Paco and Herbie by plane. They manage to find them and trick Paco into picking up a passenger. They capture him and fly off leaving behind Herbie to go for help. They find the Inca ruins and to their delight an antique gold disc. They lose the gold when Herbie captures it a drives away into the dark jungle. Thinking they've lost their money, Prindle refuses defeat. They succeed in getting the gold back and try to escape in their plane but due to the extra weight, they have problems taking off giving Herbie and Paco a fighting chance. In the end, Prindle, Shepard, and Quinn are arrested by the police, and the gold disc and confiscated and placed in a museum.