Facing foreclosure of their homes in the Goon Docks area of Astoria, Oregon to an expanding country club, a group of children who call themselves “the Goonies” gather for a final weekend together. The Goonies include optimist Mikey Walsh, his older brother Brandon, the inventive Data, the talkative Mouth and the overweight klutz Chunk.
Rummaging through the Walshes’ attic, they come across a 1632 doubloon and an old treasure map purporting to lead to the famous pirate “One-Eyed” Willy’s hoard located somewhere nearby, whom Mikey considers to be the original “Goonie”. The kids evade Brandon and make their way to an abandoned restaurant on the coast that coincides with the map; Brandon soon follows alongside Andy, a cheerleader with a crush on him; and Stef, Andy’s friend. The group quickly discovers the derelict restaurant is a hideout of the Fratelli crime family: Francis, Jake and their mother Mama. The Goonies find a tunnel in the basement and follow it, but Chunk is captured by the Fratellis and imprisoned with their deformed and immensely strong younger brother Sloth. The Fratellis intimidate Chunk until he reveals where the Goonies have gone, and begin pursuit. Chunk is left behind with Sloth, but befriends him. After Sloth frees both of them, Chunk calls the police and he and Sloth follow the Fratellis.
The Goonies evade several deadly booby traps along the tunnels while staying ahead of the Fratellis. Finally, they reach the grotto where Willy’s pirate ship, the Inferno, is anchored. The group discovers the ship is filled with treasure and they start filling their pockets, but Mikey warns them not to take any on a set of scales in front of Willy by considering that to be their tribute to him. As they leave the ship, the Fratellis appear and strip them of their loot. They make the Goonies walk the plank until Chunk arrives with Sloth and distracts the Fratellis long enough for the Goonies to jump overboard. The Fratellis proceed to grab all the treasure they can, including those on Willy’s scales; this triggers another booby trap that causes the grotto to cave in. With Sloth’s help, the Goonies and Fratellis barely escape.
The two groups emerge on Astoria’s beach, where they reunite with the Goonies’ families and the police. The Fratellis are arrested, but Chunk prevents Sloth from also being taken; he invites Sloth to live with him, which he accepts. As the kids describe their adventure to their parents, Mikey discovers that his marble bag, filled with gems he took from the ship, had not been taken by the Fratellis. Mikey’s father triumphantly rips up the foreclosure papers, declaring they have enough money to negate the foreclosure. As the Goonies celebrate, they see the Inferno, having broken free of the grotto, sailing off on its own in the distance.