The front window of Louie's Sweet Shop is a frequent victim of the local neighborhood kids' baseball games. The Bowery Boys think that a nearby vacant lot would be perfect for the kids to play ball, and keep out of trouble. Slip and Sach travel during a heavy rainstorm to visit the owners of the lot at their home on Long Island. As it turn out, the owners, all members of the same family, are completely insane. Dereck, a mad scientist, wants a brain for his gorilla. His brother Anton wants a brain for his robot, Gorog. Their sister Amelia needs fresh meat to give to her man-eating tree, while their niece Francine is a vampire. Feeling that Slip and Sach are perfect for their personal needs, the family asks the duo to spend the night. The boys soon catch on to the family's schemes, causing a frantic chase through the house. Louie, Butch, and Chuck visit the home to search for Slip and Sach, and it is not long before they too get caught up in all the madness.