Larry's perfectionist father comes for a visit and Larry wants to impress him so he can finally get a ""well done son"" from his father. But instead, they end up trapped in the basement that is flooding after Larry broke the water pipe.

Larry and Balki, Jennifer and Mary Anne, Lydia and Mr. Gorpley, and of course Larry's father are all trapped in the flooding basement. Larry attempts to solve the problem without much luck. So thinking they're all going to die, Larry must tell his father how he feels. Luck changes when Larry finds his chemistry set.