<P> King Acrisius of Argos imprisons his daughter Danaë, jealous of her beauty . When the god Zeus impregnates her, Acrisius banishes his daughter and his newborn grandson Perseus to sea in a wooden chest . In retribution, Zeus kills Acrisius and orders Poseidon to release the last of the Titans, a gigantic sea monster called the Kraken, to destroy Argos . Danaë and Perseus safely float to the island of Seriphos, where Perseus grows to adulthood . </P> <P> Calibos, evil son of the sea goddess Thetis, is engaged to marry Princess Andromeda, daughter of Queen Cassiopeia of Joppa; but for committing several atrocities against Zeus, including destroying Zeus's sacred flying horses (excepting only Pegasus), Zeus transforms Calibos into a deformed monstrous creature . In revenge, Thetis transports an adult Perseus from Seriphos to an abandoned amphitheater in Joppa, where he befriends an elderly poet named Ammon and learns that Andromeda is under a curse and cannot marry unless her suitor, upon the threat of execution if he fails, successfully answers a riddle concocted by Calibos . Zeus sends Perseus a god - crafted helmet from Athena which makes its wearer invisible, a magical sword from Aphrodite, and a shield from Hera . Perseus, wearing the helmet, captures Pegasus and follows Calibos' giant vulture carrying off Andromeda's spirit during her sleep to learn the next riddle . Perseus is discovered and nearly killed by Calibos, but manages to sever one of Calibos' hands, losing his helmet in the process . </P> <P> The next morning, Perseus presents himself as suitor and correctly answers the riddle, winning Andromeda's hand in marriage . Finding that Thetis cannot act against Perseus, Calibos instead demands that she takes vengeance on Joppa . At the wedding, Queen Cassiopeia compares Andromeda's beauty to that of Thetis herself, whereupon Thetis demands Andromeda be sacrificed to the Kraken on pain of Joppa's destruction . Perseus seeks a way to defeat the Kraken, but Pegasus is captured by Calibos and his men . Zeus commands Athena to give Perseus her owl Bubo; but she orders Hephaestus to build a golden replica of Bubo instead, who leads Perseus to the Stygian Witches . By taking their magic eye, Perseus forces them to reveal that the only way to defeat the Kraken is by using the head of Medusa, who lives on an island in the River Styx at the edge of the Underworld . The next day, the group continues on their journey without Andromeda and Ammon, who return to Joppa . </P> <P> On the Gorgon's island, Perseus fights and kills Medusa's guardian, a two - headed dog named Dioskilos . Perseus then enters the Gorgon's lair, where he uses the reflective underside of his shield to deceive Medusa, decapitate her, and collect her head; but the shield is dissolved by her caustic blood . As Perseus and his party set to return, Calibos enters their camp and punctures the cloak carrying Medusa's head, causing her blood to spill and produce three giant scorpions . Calibos and the scorpions attack and kill Perseus' remaining escorts, but Perseus overcomes the scorpions and thereafter kills Calibos . </P>

Where was the 1981 clash of the titans filmed