As the story begins, Skeletor seals the interplanetary gate between Eternia and Etheria to stop Hordak from coming. In the meantime, Adam and Teela are practicing their mid-air fighting skills.
The Sorceress alerts Adam to danger, and he rushes to Grayskull. There, he finds Skeletor trying to dig into Grayskull with the Terror Claws.
Skeletor takes Zoar as hostage, and Orko says an incantation for help, and he gets something he didn't bargain for: Hordak and the Horde show up. A battle ensues, and eventually Hordak captures everyone and imprisons them on Etheria.
The heroes break free and, after a brief skirmish with the worm monster, Orko says an incantation to take them all home. They arrive to find Hordak beating Skeletor in a duel of magic. The heroes stop Hordak and he returns to Etheria, while Skeletor curses them for helping.
This is the first of 13 issues in the MOTU series published by Marvel under their "Star" label.