One day, an old sailor, Billy Bones, appears at the Admiral Benbow Inn, where he decides to stay for a time. He becomes friendly with young Jim Hawkins, the son of the inn's owner. It is clear that Bones is hiding from someone at the out-of-the-way location, and he eventually meets up with some desperate looking buccaneers. Bones' health deteriorates from his excessive rum drinking, and when he dies, Jim finds a treasure map in Bones' trunk.
Sharing the map with Dr. Livesey and the wealthy Squire Trelawney, the squire agrees to finance an expedition to find the treasure. Before they leave the port in Bristol, they hire on an experienced, one-legged sailor known as Long John Silver to be their cook during the voyage. While on board, however, Jim overhears Silver discussing his decision to mutiny and take over the ship--and find the treasure for himself.
Silver and a large number of the crew eventually mutiny, leaving the Squire, Livesey, Jim and the ship's captain with a small group of loyal men. They are forced to abandon the ship, and they head ashore to defend themselves from the mutineers. Meanwhile, Jim discovers a forlorn castaway, Ben Gunn, who has been left on the island by the infamous pirate Captain Flint. Gunn tells Jim that he knows the location of the buried treasure.
The Squire and his men find an abandoned stockade on the island which they decide to defend. They fight off several attacks by the pirates but are eventually forced to abandon the little fort. Leaving his friends behind, Jim decides to try and make it back to the ship in Gunn's little boat. Jim overwhelms the sole remaining mutineer and hides the ship in a hidden lagoon.
When Jim returns to the stockade, instead of finding the Squire and his men, he finds Silver and the pirates. Jim follows Silver and the pirates to find the treasure, but when they reach the spot on the map, the treasure is not there. Silver is forced to defend himself from the angry pirates, but shots ring out from the Squire's hidden men. Silver joins the Squire, leaving his old mates on their own. The Squire and his men retreat to the cave where Gunn has hidden the treasure, and the men load the gold and silver aboard the ship. They eventually sail away, taking Silver with them but leaving the other mutineers behind. Before the ship reaches port, Silver steals away, never to be seen again. The others eventually return to England, rich beyond their wildest dreams.