Villagers at Valleyview Castle are celebrating the Summer Fair; commemorating the day that She-Ra saved Valleyview Castle from Hordak's Doom Balloon.
At the Fright Zone, Professor Tempus presents Hordak with his newest invention, the Time Transformer, which will permit Hordak to change losing battles into winning battles for the Horde. As the screen flashes to the time She-Ra destroyed Hordak's Doom Balloon, Professor Tempus uses a magic paintbrush to paint a second energy cannon on the Doom-Balloon, which is able to overcome She-Ra and ripple the waves of time, making Valleyview Castle Horde territory in the present.
As the Horde Troopers magically appear at the Castle, Madame Razz and Broom go to warn Adora of these new events. Hordak sees great potential in the Time Transformer, and plans to use it to definitively crush the Rebellion. When Adora learns what has happened, she and Bow resolve to go to the Fright Zone and discover the source of the disturbances. Bow and Adora are able to sneak into the Fright Zone and overcome squads of Horde Troopers, but their victory is only temporary, as they are soon captured and brought to Hordak. At that very moment, Hordak is preparing to destroy Castle Bright Moon, by changing a past defeat. The screen flashes to when Hordak attempted to use his Eclipse Beam to weaken the castle and make it vulnerable to attack, only to have She-Ra and Swift Wind physically move the moon, defeating him. Hordak plans to paint in a meteor storm to prevent She-Ra from moving the moon, and thus securing victory.
Adora and Bow free themselves and escape from the Horde Troopers, and as Bow goes to warn Queen Angella of the impending danger, Adora transforms into She-Ra. She challenges Hordak, and uses her cunning to trick Hordak into blasting the Time Transformer with his freeze cannon, disabling it, but not before it has begun to change the past. She-Ra sees only one solution: She needs Swift Wind to fly around Etheria against the rotation of the planet as fast as he can, so that they can arrive in the past. As the space-time continuum aches, She-Ra uses her strength and her sword to destroy the meteors and preserve the future. Swift Wind and She-Ra return to their present, secure in the knowledge that the Time Transformer has been destroyed.
Synopsis by Michael Cravens