A youngster finds a treasure map and befriends a pirate prior to violent battles for the treasure in this version of Robert Louis Stevenson's novel.
Jim Hawkins (Jackie Cooper) helps his mother run an inn. Billy Bones (Lionel Barrymore) arrives with a chest, orders rum for all, and sings. Blind Pew gives Billy a paper with a black spot, and Billy falls down the stairs dead. Jim finds a map in the chest and shows it to Dr. Livesey (Otto Kruger), whose carriage ran over Pew. Squire Trelawney (Nigel Bruce) gets a ship to go after the treasure.
At the harbor Jim sees peg-leg Long John Silver (Wallace Beery), who gets hired as cook and brings on a crew for Trelawney's ship. Captain Smollett (Lewis Stone) learns of the treasure and has the crew's knives cut down before the Hispaniola sails. Jim and Silver become friends. Silver gives a drunk Englishman a bottle, and he soon disappears. Henry dies falling from a yard-arm. Land is seen, and Jim hears Silver plotting to kill others too with the arms he smuggled on board. The captain plans to stay on board; but Jim goes with the crew and explores the island. Silver and his crew kill two more men who don't agree with their violent ways. Jim finds old Ben Gunn left marooned by Captain Flint to find the treasure.
Captain Smollett and his men leave the ship, shooting at the crew on board which is firing the cannon at them. Silver and the crew go back to the ship, while the captain's group raises the British flag at the fort. The ship flies the skull and cross-bones. Silver asks Smollett for the treasure chart while the captain insists they surrender and face trial. The crew attacks the fort, and several are killed with muskets and swords. Captain Smollett is wounded, but Gray saves Jim. Five against nine are left. Smollett suggests cutting the ship loose.
Jim sneaks out to the ship, cuts the rope, and sleeps on board. In the morning he takes down the pirate flag and treats Hand's wound. Jim heads the ship toward the beach. Hand with a knife chases Jim; but Jim loads his pistol and shoots Hand. He goes ashore and finds Silver at the fort. Silver tells Jim there is a treaty, but Jim is a deserter. Silver protects Jim from the crew. Silver shows the crew the map; but he keeps Jim hostage as they go after the treasure. Livesey shoots at the crew, captures Silver, and shows Jim the treasure Ben Gunn found. Smollett arrests Silver, leaves the crew behind, and sails for Jamaica. After Silver describes how he will be hanged, Jim unlocks him, and they say good-bye. Jim cries, as Silver rows away.
This adventure story allows boys and young men to identify with a courageous hero who survives treachery and finds treasure. Jim is kind even to the wicked pirates and only kills in self-defense. Silver's killing people so he can have more treasure shows how absurd greed can be.