In the mythological land of Argos, King Acrisius is enraged by the pregnancy of his unwed daughter, Danae. He punishes the young woman and her newborn son, Perseus, by confining them in a coffin and sending the casket out to sea. Meanwhile, on Mount Olympus, Zeus is incensed by Acrisius’s hubris and orders Poseidon to unleash a sea monster called the Kraken to destroy Argos. When the gods are perplexed by Zeus’s mercilessness until they learn that Perseus is Zeus’s son. The boy grows into adulthood on the island of Serifos, enjoying a life of ease and privilege, and the goddess Thetis warily compares him to her mortal son, Calibos, who lives in the town of Joppa. Since Thetis is the patron saint of the city, Calibos has been chosen by Queen Cassiopeia as the future husband of her beautiful daughter, Andromeda. As such, Calibos delights that he will soon rule the kingdom and flaunts his power, killing Zeus’s magical winged horses with the exception of one, Pegasus. Despite Thetis’s protests, Zeus punishes the boy, transforming him into a crippled ogre. When Calibos is banished from Joppa, Thetis orders her disciples to prevent Andromeda from marrying another man and places a curse of despair on the townspeople. The goddess is resentful that Perseus has enjoyed a charmed life under the protection of his father, Zeus, and magically transports the boy to Joppa so he will endure the anguish of its inhabitants. There, Perseus awakens in an amphitheater and meets a poet named Ammon. The old man warns the boy to return to Serifos, but Perseus is eager for adventure and believes his unexpected relocation is an opportunity to achieve his life-long goal, to gain sovereignty over the kingdom. Since Perseus and his mother were wrongfully banished from Argos, the boy believes he is entitled to rule the land, and his conquest of Joppa will avenge his grandfather’s misdeed. Back on Mount Olympus, Zeus orders the deities to protect his son with weapons, and the boy soon discovers “gifts” from the gods – a sword, shield, and a helmet that renders him invisible. In Joppa, Perseus inquires about a man who was recently burned at a stake, and a soldier explains that suitors risk their lives to win Andromeda’s hand in marriage. In the wake of Thetis’s curse, men must solve a cryptic puzzle to wed the princess, and their failure to do so results in death. Perseus realizes he will inherit the kingdom if he marries Andromeda and dons his helmet of invisibility to sneak into the girl’s bedroom at night. When he sees Andromeda’s spirit step into a golden cage and be carried away by a giant vulture, Perseus assumes she being escorted to Calibos and captures Zeus’s last winged horse, Pegasus, to fly to the recluse’s outpost. There, he overhears Calibos dictate a riddle for Andromeda’s next suitor. As the princess leaves, Perseus fights Calibos and cuts off his hand, but he agrees to spare the ogre’s life on condition that the curse of Thetis is lifted from Joppa. Losing his helmet of invisibility, Perseus returns to Joppa in time for Andromeda to welcome a new suitor and announce the riddle. Wielding Calibos’s severed hand, Perseus declares that the ogre’s pearl ring is the correct answer to the riddle and embraces his bride-to-be. As the townspeople celebrate their newfound liberation, Calibos prays to his mother, Thetis, begging her to punish the people of Joppa by unleashing the Kraken. Although Thetis initially refuses, she changes her mind during Perseus and Andromeda’s wedding ceremony, when Queen Cassiopeia proclaims her daughter is more beautiful than Thetis. The insulted goddess suspends the wedding and declares that Andromeda must be sacrificed to the Kraken in thirty days, or the monster will destroy Joppa. Perseus vows to kill the sea creature to protect his princess, but the poet Ammon warns him it is impossible. However, there are three blind witches who know a way to overcome the Kraken, and Perseus searches for the winged horse Pegasus to escort him on the perilous journey to find the crones. Unable to locate his companion, Perseus embarks on the quest alone, but Andromeda insists on joining her lover, and brings along her army. Meanwhile, on Mount Olympus, the goddess Athena builds Perseus a robotic owl named Bubo. The bird leads Perseus to the witches’ shrine and steals their one, shared eye. Desperate to regain their vision, the witches grudgingly tell Perseus about the sorceress Medusa, whose gaze turns men into stone. Perseus pitches the witches’ eye into the dirt and begins his journey to find the serpent-haired Medusa, leaving Andromeda behind. Using his magic sword and shield, Perseus deflects Medusa’s gaze, beheads the creature, and carries the head back to camp in a bag. There, Calibos makes a surprise attack with an army of giant scorpions, but Perseus and his soldiers fight them off, and Perseus kills Calibos. With all of his guards dead, and no time to spare before Andromeda’s sacrifice to the Kraken, Perseus knows his only hope is to find Pegasus and fly back to Joppa. Perseus orders his mechanical owl, Bubo, to find Pegasus, and the bird releases the horse from a cage, where it has been imprisoned by hunters. Back in Joppa, Andromeda is restrained on the beach and the Kraken rises from the waves, but Bubo distracts the beast and Perseus appears overhead, on Pegasus. As Perseus fights the Kraken, the monster knocks Pegasus into the ocean, and the bag containing Medusa’s head plummets into the water. However, Bubo retrieves the parcel and Perseus wields Medusa’s head just in time, turning the Kraken into stone. As the Kraken crumbles, Perseus hurls Medusa’s head into the sea and Pegasus resurfaces. Perseus reunites with his bride and the townspeople cheer, knowing their hero has brought peace and order back to the kingdom. On Mount Olympus, Zeus gloats about his son’s triumph, but the gods are concerned the boy has set a precedent. Future mortals might replicate Perseus’s independence, creativity, and courage, and see themselves as free agents who do not need the gods for inspiration. Zeus placates the assembly and forbids the deities from exacting revenge. Noting that stars never fade, Zeus commemorates the heroes of Perseus’s quest by naming constellations in their honor. Zeus declares that people will always remember the luster of the gods when they look into the night sky.