The story of a group of young New Zealand school boys. Because one of them is the nephew of a ship captain, they win the opportunity to go on a sailing trip. Some pirates (Forbes and Pike) are looking for a boat so they can go and find treasure on a deserted island. They manage to be recruited as crew members on that same boat as the school boys. After a mutiny, the pirates take over the boat and take the young boys as hostages. Helped by O'Brian, the young kids manage to escape from the pirates...