Set after Treasure Island, the tale follows Long John Silver, Robert Newton and his weathered crew as they drift through Portobello, a bustling port in the British West Indies, with little money and even less luck. Silver guards a map to a second treasure cache on Treasure Island, but the clue is useless without a special medallion to decode it. The city’s shadows deepen when Mendoza’s maniacal plot lands a much darker trap before Silver’s eyes.
The kidnapping of Elizabeth Strong, the daughter of Governor Strong, muddies the waters even further. Elizabeth, Thora Smith is seized to force the hand of the island’s rulers, while Jim Hawkins, the young cabin boy pressed into service, finds himself entangled in a conspiracy that could ruin any chance at amnesty. Jim’s fate becomes a pressing concern for both sides: the governor’s family, and Silver’s crew who would rather see the ransom paid than see the medallion discovered by anyone else. Dodd Perch, Elwyn Daniel, who has secretly aided Jim, is captured and beaten by Mendoza’s men, but his dying words point toward Mendoza, the governor, and Hawkins, setting in motion a chain of events that forces Silver to choose between old loyalties and new opportunities. The Governor, Harvey Adams Sir Henry Strong, and his wife must decide how far they will go to save Elizabeth, even as they fear what their city might become if a pirate’s plan unfolds.
During a tense ransom handoff, Silver joins forces with Billy Bowlegs to confront Mendoza aboard his ship. The two men subvert Mendoza’s plan by exposing the treacherous scheme to hoard the ransom and lure away the governor’s warships. In a cruel twist, Jim possesses the pirate medallion that reveals the map’s long-hidden location. Mendoza, seeing a chance to double-cross Silver, attempts to seize the warehouse fortune, but Silver’s crew ambushes Mendoza and wins the haul. Jim and Elizabeth seize their moment and slip away, leaving behind a scene of smoke and chaos as the two fugitives press toward a future that might end in England or on Treasure Island.
Back at the governor’s house, Jim is offered a chance to return to England, but Silver has a more ambitious plan: to take Jim with him on a second voyage toward treasure. With most of their rivals defeated and the warehouse loot in their hands, Silver sets his sights on Captain Asa MacDougall’s ship, a grim slave-ship bound for Bristol, hoping to shape their destiny on the open sea. The mission forces Silver to swerve away from an impulsive wedding with Purity Pinker, Connie Gilchrist, and instead push deeper into danger as he threads his way toward Treasure Island.
On the voyage, Silver’s mutinous thoughts surface, and he schemes to overturn Captain MacDougall. Hawkins uncovers the plan, and Captain MacDougall—staunch and puritanical—decides to maroon Silver and his men on a hidden island that serves as Mendoza’s secret hideout. Jim, in a desperate bid for freedom, torches Mendoza’s warehouse to create a distraction that allows Silver to seize Mendoza’s ship. The pirates set sail, leaving Elizabeth’s fate to be decided by the treacherous seas and the shifting winds of fortune.
Treasure Island looms as Silver and his men anchor their hope against the island’s defenses. They shelter inside a rugged stockade, where Israel Hands—now blind but once a deadly marksman—still stalks the fort. Israel’s presence tests Silver’s loyalties as Mendoza’s forces converge. The stockade is burned to the ground in the blaze of escape, and Israel’s offer to ally with Silver becomes a gamble with a price. Silver, ever calculating, accepts a temporary alliance that ensures passage to Cornwall, while vengeance against Jim remains a lingering motive for both sides.
Jim returns to the caves where the treasure is buried, pursued by Mendoza and his men. Israel attempts to kill Jim, but the resourceful boy leads him to the coast, where the vengeful pirate meets a fatal fall. Mendoza captures Jim, intending to use him as bait to lure Long John Silver into a final trap. Silver capitulates to Mendoza, but only to give his crew one last chance to strike back. A brutal battle ensues, and Mendoza’s forces are cut down, while the remaining ship’s crew is left marooned in the wake of the chaos.
With the island’s treasures secured and the last obstacle vanquished, Silver returns to Portobello as a wealthy man and dines with the Governor. The ending hints at a surprising pardon for his long history of crime, paid for with a generous donation to Government House that supposedly arms the harbor against pirates. Silver and Jim ride off into the sunset—two figures bound by a fragile truce, ready to face whatever the future holds—just as Purity Pinker looks on, her shotgun wedding dreams abandoned for the moment by the tides of fate.
