KRULL

The entity known as the Beast and his army of Slayers travel the galaxy in a mountain-like spaceship called the Black Fortress, intent on enslaving the planet Krull, as he has done to many other worlds. Ynyr recites the prophecy that was given for him to know: "A girl of ancient name shall become queen. She shall choose a king, and together they shall rule our world, and their son shall rule the galaxy."

Prince Colwyn and Princess Lyssa plan to marry in the hope that their two kingdoms' combined forces can defeat the Beast's army. However, the Slayers attack before the wedding is completed, devastating the native Krull armies, wounding Colwyn, and kidnapping Lyssa.

Colwyn is nursed back to health by Ynyr, the Old One. Ynyr tells Colwyn that the Beast can be defeated with the Glaive, an ancient, magical, five-pointed weapon resembling a large throwing star with retractable blades.[a] Colwyn retrieves the Glaive from a mountain cave, and sets out to find the Black Fortress, which teleports to a new location every sunrise. As they travel, Colwyn and Ynyr are joined by the magician Ergo "the Magnificent" and a band of nine thieves and fighters — Torquil, Kegan, Rhun, Oswyn, Bardolph, Menno, Darro, Nennog, and Quain. The cyclops Rell later joins the group.

Colwyn's group travels to the home of the Emerald Seer and his apprentice, Titch. The Emerald Seer uses a crystal to view where the Fortress will teleport next, but the Beast remotely crushes the crystal with magic. The group travels to a swamp that the Beast's magic cannot penetrate, but Darro is lost to a Slayer attack, and Menno to quicksand. A changeling agent of the Beast kills the Emerald Seer and assumes its victim's form, but the agent is discovered and killed by Rell and Colwyn.

Another changeling is instructed by the Beast to seduce Colwyn. This is meant to convince Lyssa that Colwyn does not love her. However, he rejects the changeling's advances, and Lyssa – witnessing this through a vision provided by the Beast — affirms that love triumphs over might. The Beast, though, forces her to consider marrying him so that he will halt the Slayers' attacks.

Ynyr leaves the group to seek the Widow of the Web, an enchantress who loved Ynyr long ago and was exiled to the lair of the Crystal Spider for murdering their only child. The Widow reveals where the Black Fortress will be at sunrise. She also gives Ynyr the sand of an enchanted hourglass to keep the Crystal Spider at bay and the injured Ynyr alive. As the Crystal Spider attacks the Widow, Ynyr returns to the group to reveal the location of the Black Fortress. As he speaks, he loses the last of the sand and dies.

The group captures and rides magical Fire Mares to reach the Black Fortress. The Slayers at the Fortress kill Rhun, while Rell sacrifices himself to hold open the crushing spaceship doors long enough to allow the others to enter. Quain, Nennog, and Kegan are killed as they make their way through the fortress. Ergo transforms into a tiger to save Titch from a Slayers' attack. Colwyn, Torquil, Bardolph, and Oswyn are trapped inside a large dome. The latter three fall through an opening and are trapped between walls studded with huge spikes, which kill Bardolph.

Colwyn breaches the dome and finds Lyssa. He attacks the Beast with the Glaive, which becomes embedded in the Beast's body. With nothing to defend themselves, Lyssa and Colwyn quickly finish their wedding ritual. This gives them the power to manipulate fire, with which Colwyn slays the Beast. The Beast's death frees Torquil and Oswyn, and they rejoin Colwyn, Lyssa, Ergo and Titch. The survivors make their way out of the crumbling fortress, which is pulled into space.

As the heroes return home, Ynyr repeats the prophecy that the son of the queen and king shall rule the galaxy.

Prince Colwyn and his allies infiltrate the Black Fortress, defeat the Beast, and rescue Princess Lyssa, fulfilling the prophecy.

The defeat of the Beast and the rescue of Lyssa unite the kingdoms and realize the prophecy, suggesting that love and unity can overcome even intergalactic evil. The film lands on the triumphant theme that courage and companionship, combined with a touch of cosmic magic, are mightier than advanced weaponry or sorcery alone.