On Planet Zark, Spaceman Spiff's spacecraft sits empty. The rocks are charred with death ray blasts. A struggle has taken place. Only the tracks of a sinister alien leave the scene. What has happened to Spiff? Mom is pushing Calvin into the school bus. She tells him this is humiliating. Calvin doesn't want to go.

Calvin sits at his desk with teeth gritted. He says Spiff is being held prisoner by hideous aliens. He wonders what they want with him. Spiff is called before the alien potentate. It becomes clear Spiff is going to be sacrificed....to appease the evil god they call "Nollij". Miss Wormwood tells Calvin to go to the blackboard.

Calvin, looking at the math problem on the board, says our hero thinks fast. He slowly reaches for the tiny atom blaster concealed in his belt. He turns and tells the bloodsucking, mutant chromosomal disasters that he's out of there. Miss Wormwood tells Calvin to give her the rubber band right this minute.

Spiff escapes. The smelly corridors of the fortress are deserted. All the aliens had gathered for the spectacle of our hero's demise. The space explorer makes it to the planet surface, but the alien queen is in pursuit. Miss Wormwood yells for Calvin to come back to the room. Spiff jumps into his spacecraft and blasts off. He's safe!

Mom is surprised to see Calvin at home. It's not even noon yet. Calvin tells her they were let out early due to a gas leak. Mom wonders if the school knows he left. She says she's going to call the school. Calvin tells her no one is there. Everyone was evacuated. Mom calls anyway. Spiff hadn't counted on running into a Zark enforcer ship. Spiff's evasive maneuvers come to naught.

Calvin tells Hobbes that he got in trouble when Mom found out he had just left school. She drove him back, and they had a talk with his teacher and the principal. They discussed his study habits, and now he has extra homework. Dad's going to check it every night to make sure it's right. He hands the book to Hobbes and tells him to do an extra good job. Hobbes tells him he's lucky tigers are so smart.