On a voyage, Sinbad (John Phillip Law) finds a golden tablet dropped by a flying creature. That night, he dreams about a man in black calling his name and a beautiful woman with an eye tattooed on the palm of her right hand. A sudden storm throws the ship off course, and it arrives at a coastal town in Marabia. Swimming ashore, Sinbad finds the man from his dream, an evil magician named Koura (Tom Baker), who demands the amulet.

Sinbad escapes into the city and meets the Grand Vizier of Marabia (Douglas Wilmer), the Regent since the death of the Sultan. The Vizier wears a golden mask to hide his disfigured face. The amulet, it seems, is one piece of a puzzle and the Vizier has another. According to legend, when the three pieces join together, they make a map to the Fountain of Destiny on the Lost Continent of Lemuria, giving one youth, a shield of darkness, and a crown of untold riches.

Sinbad agrees to help the Vizier and join forces against Koura, who wants to conquer Marabia. The Vizier’s face is ruined because Koura locked him in a room and set it on fire. The creature that dropped the tablet was Koura’s minion, a flying homunculus. It is spying on Sinbad and the Vizier. When they catch it, the creature is destroyed. Shortly thereafter, Sinbad meets the woman in his dream, a stunning slave girl named Margiana (Caroline Munro). Her master, Hakim (Grégoire Aslan) hires Sinbad to make a man out of his lazy, no good son Haroun (Kurt Christian) and throws Margiana in on the deal. Koura hires a ship and crew and follows Sinbad on his voyage, assaulting him with magic spells all the time.

The wooden siren figurehead on his ship is animated by Koura and steals the map. Another homunculus overhears the Oracle of All Knowledge (voice of Robert Shaw, uncredited) describe to Sinbad what he will encounter. Koura seals the men inside the Oracle’s cave, but Sinbad springs them. Koura animates a six-armed statue of Kali, which Sinbad and his men defeat. Inside the figure is the third piece of the puzzle. The natives capture Sinbad and crew, but seeing the eye tattoo on Margiana’s hand, they decide to sacrifice her to a one-eyed centaur, the fountain’s guardian of evil.

Koura arrives at the Fountain of Destiny. He drops the first piece into the fountain and the ravages of his magic on his body are restored. He summons the centaur to fight the fountain’s guardian griffin. Sinbad and the others escape, rescue Margiana, and reach the fountain. The centaur kills the griffin and Sinbad slays the centaur. Koura drops the second piece in the fountain, which makes him invisible, and he fights Sinbad with a sword.

Sinbad is losing when Koura steps into the fountain, revealing his form and Sinbad kills him. Sinbad drops in the third piece and a jeweled crown rises from the depths. Sinbad gives it to the Vizier, whose mask dissolves and reveals his restored face. They return to Marabia. When Margiana asks why Sinbad didn’t take the crown himself, he says he prefers freedom to power. They sail off into the sunset.

Christopher Lee was unable to play Koura. Tom Baker’s performance got him the role of Doctor Who, which he played for seven years, and if it wasn’t for Ray Harryhausen’s creatures, he would have stolen the whole movie. Brian Clemens was hired to do the screenplay based on Harryhausen’s sketches. Charles Schneer directed, as usual, and much of the film, as usual, was filmed in Spain. Fanboys like George Lucas and Peter Jackson were enormously influenced by Harryhausen. The film won the first ever Saturn Award for Best Fantasy Film.

Robert Shaw, on vacation, was the voice of the Oracle of All Knowledge, when the actor supposed to do it got sick, though he did want not his role credited because he thought the movie beneath him. Harryhausen paid tribute to his inspiration, the Thief of Bagdad, in several ways, notably Kali’s dance. On the shore where they land, a cliff covered in carvings was added, postproduction, to hide the spectators on the popular beach. A ship crewed by Muslims would not have a human figurehead. Because Bernard Herrmann was unable to score the film, Harryhausen got to hire Miklos Rozsa, who used part of his score for Ben Hur in the movie. The basic spells that Koura recited are “I’m cuckoo for Cocoa Puffs” and “Trix are for kids, Silly Rabbit” backwards. I imagine Tom Baker got a kick out of this.