Pugsley has been exercising, much to his parents' disapproval. Fester gets a letter from his French pen-pal, Yvette, who is coming to visit. He decides he has to get into shape, with the help of TV fitness guru Jack La Grann. Gomez and Morticia can't understand why he's doing this and think he's ill. They call in Dr. Motley, who panics at some of the results when he tests Fester and flees. When Fester accidentally hypnotizes himself in an attempt to get fit, Morticia uses the opportunity to question him. She comes to the conclusion he wants to become an astronaut. NASA isn't amused when she tries to talk them out of employing Fester, since they have no idea what's going on. Fester uses a mummy case as a steam bath to lose weight, and explains about Yvette. When she arrives, she's rather overweight and jilts Fester because he's too skinny!