It's Halloween, Billy, Mandy and Grim go trick-or-treating. Grim mistakes a woman for Atrocia, the host of the all-night Halloween marathon on TV and goes to talk to her. Upon looking at her face, Grim realizes his mistake; however, the woman mistakes Grim for her son, Gregory, and takes him home Gregory is now Grim, and does not have a stomach. At the same time, Billy mistakes Gregory for Grim and he and Mandy take him with them. In the end, Billy and Mandy take Gregory back to his mother and Grim goes back with them. Skarr is evesdropping on Hector and Dr. Ghastly about their new secret weapon—a disenigration gun. Too their dismay Estroy comes up with a better version of the gun. He also surprises them by inviting them to dinner. Hector accepts as a way to steal some of his ideas. Hector and Ghastly arrive at Estroy's neighboring island while Skarr slips around the back. Of course he falls while scaling the wall and lands in a pond of electric eels.