Prince Adam is summoned to Castle Grayskull by The Sorceress, who sends him on an urgent mission to the world of Etheria. She gives him a sword which looks exactly like his except that it has a jewel in the center, and she tells him he must find the owner, whose identity she cannot reveal. Accompanied by Cringer, Adam goes to Etheria, where he meets Bow, a rebel archer who is part of the Great Rebellion, who are aiming to overthrow the planet's dictatorial rulers, the Horde. Adam soons finds himself caught up in a conflict between the Rebellion and the Horde, and transforms to He-Man. He is attacked by the Horde's ruthless force captain, Adora, but is shocked when the sword glows in her presence. Can she really be the owner of the sword, when she is serving evil?