The main conflict in "The Pigman" arises when the main characters John and Lorraine choose to throw a party in Mr. Pignati's house while he is recovering in the hospital. When he returns to find the party going on and many of his collectible ceramic pigs broken, he dies of a heart attack. The book ends with the troubled teens contemplating humanity and their choices.
The shock of his young friends' irresponsibility hits Mr. Pignati hard after all he has been through: losing his wife, then the baboon at the zoo, who he considered his only friend. A little joy enters his life when he makes friends with John and Lorraine. Despite their initial intentions to prank him and get his money, they begin to genuinely care for him.
The party they throw is not only an act of selfishness, but is also a betrayal of Mr. Pignati's trust. John and Lorraine must also face their own personal demons in this story. Lorraine comes from a home where she feels criticized and unwanted. John appears self-confident, but underneath his facade he feels unsure of himself, as if he does not belong anywhere. Author Paul Zindel alternated perspectives from chapter to chapter between John and Lorraine as the book progresses toward the final tragedy. In the end, John and Lorraine learn lessons about true friendship and the pain of betrayal.