Cowboy and Indian, long-standing best friends and rivals, decide to celebrate the birthday of Horse, their faithful and loyal friend. They want to organize a surprise party for him and build him a wonderful hand-made barbecue. Unfortunately, when ordering the bricks for their construction, a typing error multiplies the number ordered by a billion. At first, they manage to hide away the excess bricks by stashing them on top of their roof. Later in the night though, as the party is in full swing and Horse finally plucks up his courage to approach his beloved Madame Longrée, the bricks suddenly collapse and cause a cataclysm throughout the village. Horse, Indian and Cowboy's house is destroyed. The following day, the three heroes get busy rebuilding but their new walls disappear mysteriously overnight. Horse, Indian and Cowboy start all over again and decide to keep the rebuilt walls under close surveillance. As night falls, the walls start moving and slowly disappear into the distance. The trio start chasing these strange submarine creatures, the Atlanteans, mischievous traitors and wall thieves. During their chase, they encounter an angry bear, three crazy scientists whose ambition is to cover the world in snow, and a disturbed psychopathic matriarch determined to protect her Atlantean offspring thanks to a school of bloodthirsty barracudas. At last, Horse, Indian and Cowboy win their walls back and return home only to discover that the Atlanteans have followed them and are ready to start off the final and most explosive confrontation yet.