Susie asks Calvin what's in the bag. He won't tell. He says it might come in handy today. He reminds Susie they have a history test. Susie asks if it's a bomb. Calvin asks if she and the principal wouldn't like to know.

Susie asks what's in the bag. Calvin says it's a severed head. She asks why that would come in handy for the test. Calvin explains the head is an oracle. It will tell him the answers. Susie walks off as Calvin moans "Susie is a booger brain". Calvin says it speaks the truth.

Miss Wormwood passes out the tests. Calvin asks if he can get something from his locker. Calvin won't tell her what it is. Miss Wormwood tells him to do his test. Calvin says she's spoiling a great surprise for the class. Miss Wormwood says it would be a surprise for her if he'd get to work.

Calvin starts coughing during the test. He asks to get a drink of water. He runs out to his locker to get his Stupendous Man costume.

To avoid detection, Calvin leaps into his locker to transform into Stupendous Man. Calvin can't find the handle to get out of his locker.

Calvin bangs on the locker door. He can't get out. He says this is a real job for Stupendous Man. He bangs on the door some more. He thinks this may even be a job for the custodian.

Miss Wormwood notices Calvin hasn't come back from the water fountain. Susie tells her Calvin might be at his locker, since he brought something to help with the test. Miss Wormwood walks down the hall, thinking "Five years until retirement". Inside the locker, Stupendous Man sees his nemesis, the Crab Teacher, coming for him.

Miss Wormwood opens the locker, and Stupendous Man comes out. Calvin spells stupendous, with a meaning for each letter. He gets stuck near the end and can't finish. Miss Wormwood brings Calvin back to class, complaining teachers need to also be psychologists.

Stupendous Man escapes from Miss Wormwood. He enters the classroom to do Calvin's test. Susie tells a classmate that she doesn't hardly even know Calvin.

Stupendous Man answers the test questions, then runs out of the classroom. On the way, he reminds the kids to always brush their teeth. The class sits with stunned expressions on their faces. Miss Wormwood comes in asking if Calvin has come in. Calvin walks in behind her, out of the Stupendous Man costume, wiping his mouth from his long drink.

Susie sits at her desk while she hears Calvin say they have the wrong guy. Calvin claims they want Stupendous Man. Calvin, still fighting with Miss Wormwood, asks the class to tell her it wasn't him. Susie thinks that when her Mom asks how the day at school was, she'll just say "fine" and change the subject.

Calvin explains to Hobbes that Mom took his costume away. Hobbes asks if Stupendous Man has ever won a battle. Calvin says they're moral victories. Calvin tells him that he also flunked the test.