Chapter 1: The narrator (Gene) returns to the Devon School in New Hampshire, that he graduated from 15 years earlier. He goes to a certain tree and switches back to the past. Phineas dares everyone to jump from a branch in the tree into the river. Phineas, and Gene both jump. On the way back Phineas and Gene play fight so that they are late for dinner.
Chapter 2:Mr. Prud'homme, a master, stops by the boys' room to scold them for missing dinner again for the ninth time in two weeks. Phineas explains that they were late because they were jumping out of the tree to toughen up for the war. Mr Prud'homme, accepts the explanation because, he, and everyone else, feel sorry for the boys that will soon have to go to war.
Chapter 3: The boys join The Super Suicide Society of the Summer Session. The club meets every night.
Phineas and Gene open each night by jumping out of the tree. They make a new kind of war game called blitzball, in which everyone is everyone elses enemy. Phineas breaks the schools swimming record, but tells Gene not to tell anyone, he just wanted to do it for himself. Gene and Phineas of campus to the ocean to swim. They have a drink at the bar, the spend the night on the beach, and Phineas tells Gene he is his best pal. Gene is not sure if he feels the same.
Chapter 4: Gene and Finny (Phineas) wake up and head back to Devon. Gene fails his trigonometry examination for the first time. Finny tells Gene that he studies too much. Gene thinks Finny is jealous. Gene wants to earn the Scholastic Achievement Citation to get even with Finny. Gene knows that Finny must be best and...