The narrative begins with Tom Sawyer grappling with the ambiguity of his recent experiences. Despite being "tormented" by dreams of the "rich treasure" slipping through his fingers, he seeks confirmation from Huck Finn. Their meeting reveals a shared anxiety; Huck, sitting dejectedly on a boat, laments, "If we left those blame tools at the dead tree, we'd have got the money." This exchange confirms that their discovery was not merely a "dream," but a tangible, albeit lost, opportunity that now demands action.
The boys turn their attention to the enigmatic phrase "number two," which they initially struggle to interpret. Huck notes the absurdity of the concept in their "one-horse town," suggesting there are no numbered houses. They eventually deduce it must refer to a room in an inn. Upon investigation, they find that while the reputable inn’s room number two is occupied by a lawyer, the "shabbier lodge" holds a more suspicious secret: the room is kept locked and is only accessed under the cover of darkness. This discovery cements their suspicion that this is the lair of the "devil Injun Joe."
Driven by the prospect of wealth, the boys initiate a surveillance plan. Tom devises a strategy to procure keys and wait for an opportune night to infiltrate the inn. The atmosphere of their stakeout is thick with tension; the environment is described as having "perfect stillness interrupted only by the mutter of distant thunder." On Thursday night, Tom, equipped with Aunt Polly's "old tin lantern" obscured by a towel, ventures into the "pitch-black alley" to confront the mystery head-on.
The mission takes a harrowing turn when Tom returns in a state of panic, shouting, "Run for your life!" In the safety of a deserted barn, Tom recounts his narrow escape. Upon entering the room—which was unlocked—he discovered Injun Joe "lying there sound asleep on the floor." Tom admits that in his terror, he failed to locate the box or the cross, noting only a "tin cup on the floor." This close call serves as a sobering reminder of the danger they are courting.
Following the frightening encounter, the boys decide to pivot their approach. Acknowledging that the situation is "too scary," Tom suggests a more cautious methodology: "Let's not try anything else until we know Injun Joe's not in there." They agree to maintain a vigilant watch over the tavern, waiting for the moment Injun Joe departs, at which point they plan to "snatch that box quicker than the lightning." The chapter concludes with the boys retreating, their minds filled with the anticipation of the "riches that would soon be theirs," setting the stage for a high-stakes confrontation.