The next morning, a Sunday, Huck creeps to the Welshman’s house and learns that the whole town is out looking for the deaf and mute Spaniard and his companion—both of whom the old man and his sons chased away the night before. (The Welshman does not yet know the Spaniard’s true identity.) Huck then describes how he followed the intruders the previous night. He tries not to mention the treasure, but eventually he describes the deaf and mute man’s speech and so has to admit that the Spaniard is actually Injun Joe. The Welshman tells him that the package the two men were carrying contained burglary tools, which relieves Huck considerably, because it means that the treasure must still be in the tavern.
Soon everyone has heard about the events at the widow’s house, but the Welshman keeps the identity of the boy who saved the widow a secret, in order to make it a great surprise. At church that morning, everyone discusses the excitement, and then Mrs. Thatcher asks Mrs. Harper where Becky is. Mrs. Harper says that Becky did not stay with her, and then Aunt Polly appears, wondering where Tom is. Eventually everyone realizes, to a collective horror, that Tom and Becky must still be in the cave.
A search party is organized and sets out for the cave immediately. The day drags on with no word from the missing children, and Huck, meanwhile, acquires a fever. The Widow Douglas, who remains ignorant of Huck’s actions the previous night, takes care of him. Eventually, the searchers in the cave begin to give up—the only traces found of the children are the words “BECKY & TOM,” written on the cave walls in candle-smoke soot, and one of Becky’s ribbons.
In the days that follow, the town discovers that Temperance Tavern serves liquor. When Huck wakes from his feverish sleep at one point, he asks Widow Douglas if anything has been found at the Temperance Tavern. She tells him that alcohol has been discovered and the tavern shut down, so Huck assumes the treasure is gone. Tom and Becky remain lost.
The story returns to Tom and Becky on the day of the picnic. They wander away from the larger group, exploring and using smoke to make marks on the walls so that they can find their way back. Eventually, they come to a large room filled with bats, and the bats attack them and chase them into unknown passages. After escaping the bats, they realize how far from the others they are and decide to go back, but they cannot go the way they came, as the bats are blocking it. Tom chooses another passage to follow, and, after a while, they realize they are completely lost. Tom hasn’t made any marks, and even finding the bats again seems impossible.
The couple wanders on, occasionally calling for help. Becky sleeps for a time. When she wakes up, they realize that their parents will not miss them until the following day. Despair sets in for a while. They then hear the voices of rescuers and call in reply. The search parties do not hear them, and the children find their way blocked by crevices and pitfalls. The voices grow fainter and eventually cease. The children grope their way to a spring and sit down, knowing they will soon run out of candles.