Original Aridate: ?/?/1985
Melaktha and Adam go on an expedition to find Avathar Island, home to the ruins of the ancient Avathar Empire. Trap Jaw steals onto their ship disguised as a sailor to find out what Prince Adam is doing. They float to Avathar Island, where Melaktha finds an entrance to an ancient museum. Moss Man discovers the entrance to the Ancient Mirror of Avathar, which holds the entire knowledge of the Avathar Empire. They take the mirror away in the ship, but a storm severely hinders their ability to reach land. Young Opie, left in charge of the lighthouse by his father Angus, discovers that the light has stopped.
Adam and Moss Man discover the stowaway Trap Jaw and imprison him. The storm creates a hole in the bottom of the boat, letting water flood in. Angus returns and the two of them use a mirror to reflect the beacon light in the right direction. Moss Man's seaweed plugs the hole in the ship, and He-Man ties a rope to his waist and swims the ship back to land.
Synopsis by Zadoc Angell