When I.R. Baboon gets jealous that I.M. Weasel has been 1st on Mars, Jupiter and Uranus, Weasel rejects NASA's plan for sending him to the Sun, which gives I.R. the chance to be the 1st astronaut to Sun.
Getting a fake I.D. enables I.R. Baboon to fulfill his dream of being a captain of a deep see tour, but he takes his bathysphere too deep and hits bottom when the submersible's rope snaps. Can I.M. Weasel save Captain I.R. and his frantic tourists ?
When Weasel wins the starring role of a new film that Baboon was after, Baboon steals Weasel's skin, making Weasel unable to show up on set. This leaves Baboon, who is now disguised as Weasel, to take his place.
When the Women's Naval Auxillary holds a ping-ping tournament for a fund-raiser, their best player is in a freak accident, so Weasel, a ping-ping master who has retired, is called to play. Infuriated, Baboon sneaks in just to have a grand face-off with Weasel... and he sadly succeeds.
Baboon takes the last specimen of a rare thistle, and nearly kills it. When plant doctor Weasel is called in to investigate, he learns that Baboon has created a type of baboon/plant hybrid, that Baboon has now decided to marry.
An accident causes Weasel and I.R. to drop their brains and they become unconscious for a part of time. The man who finds them gives Weasel I.R.'s brain and I.R. Weasel's brain while they are unconscious.