Krull is a 1983 herioc fantasy sci-fi film, starring Ken Marshall.
A narrator describes a prophecy regarding "a girl of ancient name that shall become queen, that she shall choose a king, and that together they shall rule their world, and that their son shall rule the galaxy".
The planet Krull is invaded by an entity known as "The Beast " and his army of "Slayers," who travel the galaxy in a mountain-like spaceship called the Black Fortress. In a ceremony involving exchanging a handful of flame between the newlyweds, Prince Colwyn and Princess Lyssa attempt to marry and form an alliance between their rival kingdoms in the hope that their combined forces can defeat the Beast's army. A prophecy foretells that Lyssa will bear a child destined to rule the galaxy. The Beast has his Slayers attack the wedding before it is concluded. The castle of Lyssa's father, King Eirig, is destroyed and the Kings are murdered. The Kingdoms' armies are devastated and the princess is kidnapped.
Colwyn, the only survivor, is found and nursed by Ynyr the Old One. Colwyn sets out to rescue Lyssa, but Ynyr tells him in order to defeat the Beast he must find the Glaive," an ancient, magical, five-pointed throwing weapon with retractable blades which Colwyn retrieves from a high mountain cave. He learns from Ynyr that he must also track down the Black Fortress, which teleports to a new location every day at sunrise. As they travel Colwyn and Ynyr are joined by an accident-prone magician, Ergo "the Magnificent", and a band of nine fugitives led by Torquil. Colwyn enlists the convicts' aid and in return offers them their freedom as their reward. Torquil's group of thieves, fighters, bandits, and brawlers include Kegan, Rhun, Oswyn, Bardolph, Menno, Darro, Nennog, and Quain, who each has minor, notable roles in the story. The cyclops Rell (who possesses the ability to know when his time of death arrives), also joins the group after first following them from a distance.
To help them find the Black Fortress, Colwyn's small army travels to the home of the blind Emerald Seer, and his young apprentice Titch. The Emerald seer uses his emerald crystal to try and view where the fortress will rise but the beast's hand rises out of nowhere and crushes the crystal before the group can discover the location. The Emerald Seer tells the group that the only place where the beast's power cannot overcome his vision is a place in the swamp. Ynyr persuades the Emerald Seer to go to the swamp with them.
The group is attacked by Slayers as soon as they reach the swamp taking Quain and Nennog lives. The Beast has the Seer killed before he can reveal the location of the Fortress. While the group rests up in a forest near a village, Kegan goes to the small town and gets Merith, one of his wives, to bring food and to cook for their tired group. While they are eating and resting, Merith's assistant, under the remote command of the Beast, tries to first tempt and later, when the temptation fails, kill Colwyn. He escapes the assassination, which causes the assistant to reveal she is jealous of Colwyn and Lyssa's love. The Beast, enraged by her inability to kill her target, kills her instead.
Ynyr does not camp with the others though as he momentarily leaves to journey to the Widow of the Web for assistance in finding the Black Fortress. The Widow of the Web is actually an enchantress, also named Lyssa, 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 Beast's Fortress will be at sunrise. She also gives Ynyr the sand from the enchanted hourglass that kept the Crystal Spider from attacking her and will keep Ynyr alive as long as he can continue holding the grains in his hand. Ynyr quickly flees the web as the Crystal Spider attacks the Widow's prison and begins to destroy it. Ynyr returns to the group to reveal the news before he loses the last of the sand, which kills him.
Colwyn and his followers use captured Fire Mares—the only transport fast enough to reach the teleporting fortress in the same day—to reach the Black Fortress, but are attacked by Slayers, who kill Rhun. Upon finding a way in, Rell uses his tremendous strength to hold open the huge doors long enough for the others to enter. While this happens, additional Slayers attack, killing Darro. After everyone else enters, the entrance closes, crushing Rell. The group then attempts to cross a bridge, but as they make their way across, Menno is killed by a Slayer.
Shortly afterward, as they make their way through the Fortress, the group is further reduced when Kegan sacrifices his life to save Torquil. To make matters worse, Ergo and Titch get separated from the others. When the Slayers try to kill Titch, Ergo magically transforms into a tiger and kills the Slayers, injuring himself while saving Titch's life.
Colwyn, Torquil, Bardolph, and Oswyn reach a spacious area with no apparent exits, containing a large dome. As Colwyn attempts to open a portion of the dome with the Glaive to find either another passageway and/or Lyssa, Ergo and Titch, Torquil, Bardolph, and Oswyn attempt to find another entrance to the curved structure by walking around its circumference. When one is not immediately located, they are surprised when Bardolph falls through a wall facing the dome. Torquil and Oswyn go after him and the three bandits find themselves caught in a trap with slowly closing walls studded with huge spikes. In an attempt to reach a fallen dagger, Bardolph loses his life.
Meanwhile, upon opening a section of the dome, Colwyn finds Lyssa and confronts the Beast, injuring it with the Glaive. However, he is unable to recover the Glaive from the Beast's body. With nothing to defend themselves against the Beast's counterattack, Lyssa realises that together, their ability to project flame can finish the Beast. They quickly finish the wedding ritual and the two use the flame to slay the Beast. Its death frees Torquil and Oswyn from the spike room and the two soon find their way to Colwyn and Lyssa, who retrieve Ergo and Titch as they all make their way out of the crumbling Fortress. The survivors watch as the Black Fortress crumbles and is sucked up into the sky. Colwyn names Torquil as Lord Marshal, which Torquil accepts.
As the surviving heroes depart across a field, the narrator (Ynyr) repeats the same prophecy from the beginning, implying that the queen and her chosen king mentioned there (whose son shall rule the galaxy) are Lyssa and Colwyn respectively.