The Pigman centers on two teenage protagonists, John Conlan and Lorraine Jensen, who alternate chapters to tell the true story of their experience with Mr. Pignati, a man they call the Pigman. The book opens with a one-page preface that establishes this context with a signed oath explaining John and Lorraine’s purpose in writing. The rest of the book is told in flashback, a technique that helps propel the plot forward because early on the reader learns the end of the story—Mr. Pignati dies—and wants to find out what happened to him and how John and Lorraine are involved in his death.

The conflict in the novel is unusual since no true antagonist exists. Rather than pitting John and Lorraine against their unsupportive parents or against their “berserk” classmate Norton, the novel’s conflict is mainly internal. The teens’ biggest battle rages within themselves as they seek to understand their own confused emotions around more existential ideas like feeling loved, making human connections, and taking responsibility for their actions. One could say the antagonist is John’s and Lorraine’s own inner demons.

For much of the book, the conflict focuses on John’s and Lorraine’s efforts to figure out how they want to live their lives and what kind of people they want to be, though they don’t recognize this happening in the moment. Becoming friends with Mr. Pignati is the catalyst that forces them to challenge their ways of behaving, and the inciting incident that sets the plot in motion is Lorraine’s prank phone call, which introduces them to the person who will make them examine their own motivations, responsibilities, and futures more closely. Their first trip to the zoo is another key event because this outing gives them the opportunity to discover that they enjoy hanging out with Mr. Pignati and builds the foundation for a friendship with this older man. Another notable event is the trip to the department store in Manhattan, in which John, Lorraine, and Mr. Pignati spot three monkeys in the pet store clinging to one another. To Lorraine, these monkeys represent the threesome and their search for love and acceptance. After the trip to the store, the trio draw even closer, spending time together almost every day. Lorraine and John feel compelled to tell Mr. Pignati the truth about their initial meeting, that they are high school kids, not charity workers, and Mr. Pignati responds by confessing that he lied too and his wife, Conchetta, is dead.

Problems arise when Mr. Pignati, trying to keep up with the energy level of teenagers, suffers a heart attack and is hospitalized. During this time, John and Lorraine are at liberty to use Mr. Pignati’s house as their own, and on the very first evening, they play at being adults, making dinner, drinking wine, dressing up in the Pignatis’ clothes, and imagining themselves as glamorous actors. John and Lorraine’s game ends in an unexpected kiss, an awkward moment because Lorraine has a crush on John and has no idea if the kiss means anything to him. The unusual distance between John and Lorraine in the ensuing week makes it easier for Lorraine to accede to John’s desire to hold a party at the house. Toward the end of the novel, dozens of teenagers are eating, drinking, and dancing in Mr. Pignati’s house while Mr. Pignati remains in the hospital.

The climax of the story comes at the party when Norton shows up. Even though Norton was not invited, John, fearful of what Norton might do, welcomes him in. Norton does not disappoint, quickly moving to steal anything of value he can find. When John challenges him, it seems to trigger Norton into going “berserk,” a description that has been applied to him for many years. Instead of being content with the stolen items, Norton starts breaking Mr. Pignati’s beloved pig figurines in the pig room, hoping to find money inside. John, drunk and furious, attacks Norton, and the two boys fall to the floor in front of Mr. Pignati, who has returned home from the hospital earlier than expected.

The remainder of the story focuses on the fallout from the party. John and Lorraine face their parents, who will never understand their children and thus can’t help them. Their attempts to patch up their relationship with Mr. Pignati turn tragic when they persuade him to meet them at the zoo to visit his beloved baboon, Bobo. Unbeknownst to them, Bobo had died while Mr. Pignati was in the hospital. When Mr. Pignati learns of this news while standing in front of Bobo’s enclosure, he suffers another heart attack, this one fatal. He could not bear yet one more “betrayal” by a friend. John, left to narrate the final chapter, finds his thoughts wandering from the dead Mr. Pignati to his own internal conflicts about what kind of person he wants to be and what kind of person it is possible for him to be. John realizes that he, Lorraine, and Mr. Pignati all trespassed in a place they didn’t belong. He and Lorraine went forward in time and tried to be adults before it was their time, Mr. Pignati went backward and tried to be childlike, and now they are all being punished. At the end of the novel, John takes Lorraine’s hand, and they exchange looks, both of them understanding that they are, indeed, the only ones responsible for their own lives.