The narrative commences at a harbourside inn in Bristol, where the protagonist, Jim Hawkins, encounters a "salty old sea captain named Billy Bones." The plot accelerates following Bones’s sudden death, which reveals a "wooden sea chest" containing a "stained, spotted piece of paper." When Jim presents this artifact to Dr. Livesy and Squire Trelawney, they immediately identify it as a "treasure map" once belonging to the "notorious pirate Captain Flint," complete with a "big X marking the spot." This discovery sets the trio on a perilous journey to locate the hidden gold.
In their haste to embark, the group secures the ship Hispaniola and hires Captain Smollett. However, their judgment is clouded when they encounter Long John Silver, a "fearsome man with one leg, gold teeth and a parrot on his shoulder." Despite Captain Smollett’s intuition that Silver and his men are "former pirate shipmates of Captain Flint," the squire and doctor foolishly hire them. The tension reaches a breaking point when Jim overhears Silver plotting a "mutiny," intending to "kill Captain Smollett and take the top spot and the treasure for himself."
Upon reaching the island, the situation deteriorates rapidly. Jim finds himself in a "hot spot" as the pirates' "treasure lust is released." While hiding, Jim witnesses the brutality of the antagonist, noting the "ground spotted with blood" where Long John Silver murdered a sailor who refused to join the rebellion. Amidst this "carnage," Jim encounters Ben Gunn, a "wild, half-crazy man" who reveals that he was abandoned by Captain Flint years prior and had been living on the island, aware of the treasure's general location.
The conflict culminates in a "terrible battle" after Captain Smollett "spots the enemy's position." Long John Silver, in a desperate attempt to maintain control over his "cutthroat gang," leads them to the location marked on the map. However, the pirates are left in shock to find the "treasure gone." The climax sees Smollett and Ben Gunn intervene, forcing the pirates to scatter. It is revealed that Ben Gunn had already discovered the gold and silver, keeping it safe in his cave.
The story concludes with a surprising turn of events regarding Long John Silver. Having "seen the error of his ways," he assists Jim in reuniting with the others, leading them to the hoard of "gold and silver beyond their wildest dreams." The tale serves as a moral reflection, suggesting that while the pirates were driven by greed, even a pirate can "change his spots" under the right circumstances. The journey proves to be an unforgettable adventure that truly "hit the spot" for those involved.