The Clubhouse Gang is spending the day hanging out at the beach, when the pirate'y Pegleg Pete sails to shore with a note for Goofy from his long lost Grandpappy, Captain Goof-Beard (voiced by Dick Van Dyke). Seems that there be trouble at his home, Harmony-Chord Island, a musical island which is going out of tune and will soon sink into the ocean! Cap'n Mickey and his crew of Clubhouse mateys sail on a pirate ship (The Jolly Golly) and set out to help Captain Goof-Beard save Harmony-Chord Island. On the island, Captain Goof-Beard welcomes Mickey, his grandson Goofy and the rest of their pals who follow a trail of musical clues that lead to the treasure which helps put the sinking island back in ship-shape! Yo ho ho, and a do-re-mi!