Tom Sawyer and Huckleberry Finn play hooky from school and have a plan to revive a dead cat with the spirit of a man named Hoss Williams who is on his death bed. Sawyer and Finn talk with Muff Potter, the town drunk, but are interrupted when Injun Joe says that Doc Robinson wants to see them. Muff and Joe meet Robinson and he informs them that they have a job to dig the grave of Williams. Joe is angry that Robinson didn't fix his leg correctly. Meanwhile, Tom continues to skip school and comes up with fantastic stories about why he's not home for dinner, where he tricks the children of the town to do his punishment chores for him.
After Williams dies, the two go to the cemetery and find out that Muff and Joe are digging up a grave on the advice of Robinson. Joe continues to be angry at Robinson and demands more money for the job. When Robinson refuses, Injun Joe picks up a shovel, accidentally knocking Muff out, hits Doc Robinson into the grave with the shovel, then grabs Muff's knife and jumps in after Doc Robinson. Tom and Huck witness all this and then run off, making a pact not to tell anyone what they saw.
Joe frames Muff for the murder and Muff goes to jail. Meanwhile, the beautiful Becky Thatcher moves to town which sends Sawyer into a romantic daze. At the trial for Muff, Tom is unable to contain himself as Joe is called to the stand and lies about the incident, continuing to frame Muff for the murder. As Tom is called to the stand, he relates what happened, not mentioning that Huck was with him. Suddenly, Injun Joe throws a knife at Tom, narrowly missing Tom's head and jumps out the window of the courthouse, fleeing.
After the trial, Tom and Becky get "engaged" but that quickly ends when Tom mentions he's also engaged to Amy Lawrence. After sulking, Tom is attacked by Finn for "breaking the pact" and they both decide to run away. While paddling down the Mississippi, their raft is capsized by a passing riverboat and they end up on an island where they enjoy freedom and muse over what happened to Injun Joe. While on the island, they witness some people "dragging the river", a process where a cannon is fired to bring up any bodies from the bottom of the river.
Tom and Huck decide to "go home" and find out that there's a funeral being held for them. The funeral service breaks up when Judge Thatcher sees them in the back of the church. The Widow Douglas takes Finn under her wing after that. Later, at an Independence Day celebration, Tom and Becky go into McDougal's Cave for a drink of water from the underground spring and run into Injun Joe. Joe chases them through the cave, intent to kill Tom. However, Judge Thatcher, Muff and Huck catch up to Joe and Muff tosses a torch at Joe who falls to his death afterwards. Later, Huck disappears, worrying the Widow Douglas and Tom finds him at the old fishing place where they hang out. Tom berates Huck for worrying Douglas, and Muff decides to leave the town.
Who decides to leave the town?
Muff