When Herman fools around with a ham radio in Grandpa’s dungeon, he thinks he’s contacted Martians. But he is actually speaking to two kids who are fooling around with walkie-talkies and just pretending to be Martians. The kids think Herman is also a kid, and a stupid one too.

Eddie needs an impressive pet to take to the school pet fair, but Spot, the fire-breathing monster, is too shy to come out of hiding. Eddie decides to take Igor the bat, but Igor is insulted by one of Herman’s wisecracks and flies away. Without Eddie’s knowing, Grandpa changes himself into a bat to impersonate Igor. This causes trouble when Eddie gives Grandpa to another student whose father wants to send him to outer space on a scientific mission.