Producer Carl Denham returns to Skull Island in search of more monsters.

Hounded by reporters, cited as a defendant in numerous lawsuits, and on the verge of being indicted by a grand jury for his involvement in the ill-fated promotion of King Kong, the giant ape, Carl Denham flees New York with his friend, Captain Englehorn, and sets sail for the East Indies. Unsuccessful in their try at the shipping business, Denham, Englehorn and their crew make a stop on the island of Dakang. There they meet pretty Helene Peterson, the sad-luck singer in a traveling show operated by her alcoholic father, and the treacherous Captain Helstrom, who is being investigated by local authorities for the mysterious destruction of his last ship. After Helstrom has a drunken fight with Helene's father, which results in a fire and the showman's death, Helene stows away on Denham's boat, unaware that it is bound for Kong's island. Lured back to the island by Helstrom's stories of hidden treasure, Denham, Helene, Englehorn and Charlie, the cook, are thrown off their boat by a mutinous crew, who have been egged on by the cowardly Helstrom. After reluctantly picking up Helstrom, who also is tossed overboard, the group reaches Kong's island in a dinghy, but is forced by the natives to land on the Skull Mountain side, where prehistoric creatures roam. While exploring the area, Denham and Helene find a baby-sized King Kong and, feeling guilty about the fate of his father, rescue him from a pool of quicksand. Son of Kong protects them from and does battle with various giant creatures, and they in turn bandage his wounded finger. With baby Kong's help, Denham and Helene find the natives' treasure, but at that moment, an earthquake hits and the group must quickly flee the self-destructing island. After Helstrom is killed by a hungry sea monster while stealing the dinghy, Denham is saved from drowning by little Kong, who dies nobly in the effort. Rescued by a passing ship, Helene then proposes to the treasure-enriched Denham.