For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Tom falls in love with the new girl Becky Thatcher, but things get complicated when he and his friend Huck witness Injun Joe kill a man and then frame Muff Potter.
Act II
Tom, Joe Harper, and Huck run off to an island and subsequently witness their own funeral. Tom saves Muff Potter by testifying at his trial, but he fears the newly escaped Injun Joe may be out to get him. Tom and Huck go hunting for treasure, only to run across Injun Joe once again. They put their lives on their line in order to get the money.
Act III
Huck saves the Widow Douglas from being murdered by Injun Joe. Tom gets lost in a cave with Becky Thatcher, and nearly gets killed by Injun Joe, before escaping from the cave. Injun Joe dies. Becky loves Tom. Tom loves Becky. Tom and Huck get the treasure from the cave. Everyone lives happily ever after.