Even though Injun Joe is the antagonist, Tom never lost hope and just figured out a way to help himself and Becky get out of the cave. Tom and Becky finally found their way out of the cave and was recovering from there long adventure, but while Tom and Becky were in the cave they weren't alone since Injun Joe was in the cave too. So after a few days from healing Tom finds out the cave was shut down and no one can go inside meanwhile Injun Joe was still inside! After Tom arrives to the Thatcher's house to see Becky, Mr. Thatcher explains, "Because I had a big iron door put over the opening two weeks ago. The door is triple-locked--and I've got the keys!" In other words, Mr. Thatcher locked up the door so no one could get lost in the cave anymore.