The novel opens with Aunt Polly searching for Tom Sawyer, the young protagonist of the novel who, along with his younger brother Sidney, was sent to live in St. Petersburg, Missouri, after his mother's death. After hearing no answer to her calls, Polly finds Tom eating out of the jam closet. Tom escapes Aunt Polly's beating by diverting her attention, leading Polly into a tirade against Tom's irreverent ways.
During dinner, Aunt Polly tries to trick Tom into admitting that he played hooky from school that day to go swimming. But Tom, aware of Aunt Polly's motives, has sewn his shirt collar back in place after his afternoon swim. Aunt Polly apologizes to Tom for her suspicions, until Sidney - notorious for being "the Model Boy of the village" - points out that Tom's shirt is sewn together with black thread instead of the white thread that Aunt Polly had used that morning. Before she can punish him, Tom darts out the door and runs away from the house.