Tom arrives home to find Aunt Polly filled with righteous anger.
Thanks to Tom, she's been made to look foolish: she told Mrs. Harper about Tom's amazing dream, only to find out that Joe Harper had told his mom every last thing about Tom's escapade.
Tom uses the old "I didn't think," defense to try and get out of the jam, but Aunt Polly's not in the mood for such talk.
So Tom says to her, no, really, I swear, I came back to tell you I was OK, but by now he's got just about as much credibility as The Boy Who Cried Wolf.
Aunt Polly tells him she'd like to believe him, but that she simply can't anymore.
Tom tells her all about the bark and he, smooth criminal that he is, actually gets her to believe him.
After she sends him back to school, she heads over to the closet and pulls out the coat he was wearing on the island; she wants to know if he was telling the truth. Lo and behold, she finds the bark, and she thanks the Lord that he did, this time, tell the truth.