Tom Sawyer doesn't like school much. Escaping from the schoolhouse, he's off to the woods to catch a wild pig with his friend Huck. Their attempts to sell the pig at the harbor end with a wild disturbance on the steamboat.
Tom is dismayed when Aunt Polly tells him he must spend his Saturday whitewashing the fence. Too long to paint in one day, Tom convinces his friends of the joys of the job, and soon has all the help he needs.
Tom goes to the harbor to meet his cousin Mary, and sees Becky Thacher for the first time. Her family moves into St. Petersburg, and Tom falls in love.
Tom arrives at school late and finds that Becky is in his class. He finally manages to become friends with her, and promises to visit - forgetting another promise he has made to Huck.
Huck is offended that Tom forgot his promise. The next few days Tom works with Huck, telling Becky he is busy helping his sick aunt. Becky discovers his lie but her anger is replaced with surprise when she sees Huck's newly built tree house.
Tom just can't get along with his new classmate Alfred, and challenges him to a fighting match. On the way home, the boat they are aboard sinks and Tom rescues Alfred, who can't swim at all - winning Becky's praise.
A large steamship comes to St Petersburg. Tom and Huck steal aboard for a trip. Next day, Tom boasts about their adventure, fascinating his classmates.
After Becky ignores Tom for five days, he decides to run away from home to be a pirate. During the night he sails to Jackson Island on a raft, along with Huck and Ben.
Sid comes down with the mumps just as summer vacation starts. Tom doesn't want to get sick and spoil his holiday. Just then two men come to town with Water of Life, guaranteed to cure every disease.
Tom discovers a dead body up the river - it appears to be Huck's father! After the funeral, Huck's father appears alive; come to take his son. Huck doesn't want to go, and hides.