Clash of the Titans spoilers explained

What is the main twist in Clash of the Titans?

The primary twist is that Calibos, the monstrous son of Thetis (Maggie Smith), is actually the rightful prince of Joppa whom Zeus (Laurence Olivier) cursed for killing Pegasus. Thetis schemes to destroy Perseus (Harry Hamlin) and Andromeda (Judi Bowker) as revenge. Perseus must use the severed head of Medusa to turn the Kraken to stone, but he cannot look directly at her, using a reflective shield. Additionally, the mechanical owl Bubo is a gift from the gods that proves crucial in locating the Stygian Witches.

What happens in Clash of the Titans?

The film opens on Mount Olympus, where Zeus (Laurence Olivier) has taken Danaë as his mortal lover and fathered a son, Perseus. Danaë and the infant Perseus are cast into the sea by King Acrisius, but they survive. Years later, on the island of Seriphos, the young adult Perseus lives with his mother and the fisherman Dictys. Dictys’s brother, the king Polydectes, covets Danaë and arranges a feast where all guests must bring a horse. Perseus, who has no horse, boasts he could bring the head of Medusa instead. Polydectes seizes this and sends Perseus on a seemingly suicidal quest.

Zeus, watching from Olympus, decides to aid his son. He sends Hermes to guide Perseus and gives him a magical sword, a helmet of darkness (which renders him invisible), and a polished shield from Athena. Perseus also receives a mechanical owl named Bubo, a gift from the goddess Hera. Perseus travels to the lair of the Stygian Witches, three blind hags who share a single eye. He steals the eye and forces them to reveal the location of Medusa’s island. They tell him and also reveal that Medusa’s gaze turns flesh to stone.

Meanwhile, on Olympus, Thetis (Maggie Smith), a sea goddess, is angry because Zeus cursed her son Calibos. Calibos, once a handsome prince of Joppa, killed the winged horse Pegasus, so Zeus turned him into a monstrous, goat-legged creature. Thetis vows revenge against Zeus and his mortal children. She learns that Perseus is Zeus’s son and manipulates events in Joppa, where Queen Cassiopeia (Siân Phillips) has boasted that her daughter Andromeda is more beautiful than Thetis herself. In fury, Thetis demands that Andromeda be sacrificed to the Kraken, a massive sea monster, unless the riddle of Calibos is solved.

Calibos is the rightful fiancé of Andromeda, but his curse makes him vile. Andromeda does not want him. Perseus, still on his quest, encounters Pegasus, who has been tamed by Calibos. Perseus captures Pegasus and flies to the island of Medusa. In a tense battle, he confronts Medusa in her temple, using his shield to avoid her gaze, and beheads her. He places the head in a bag and flies away on Pegasus, but Calibos shoots an arrow that wounds Pegasus; Pegasus plunges into the sea and disappears (he later returns).

Perseus arrives at Joppa just as Andromeda is chained to a rock by the sea, awaiting the Kraken. The citizens believe Calibos is a monster, but Perseus learns the truth. Thetis’s spell forces Andromeda to be sacrificed. Perseus confronts Calibos in a swamp and defeats him. He then rides to the shore, where the Kraken emerges. He uses Medusa’s head, holding it up before the Kraken, and the monster turns to stone. The stone Kraken crumbles into the sea. Andromeda is freed.

Back in Seriphos, Perseus returns to stop Polydectes from forcing his mother into marriage by revealing the Medusa head and turning the king and his court to stone. Perseus then makes his mother a priestess of Athena and gives the winged sandals and other gifts back to the gods. He chooses to remain mortal and marry Andromeda. The gods on Olympus are satisfied, and Thetis begrudgingly accepts the outcome. Perseus and Andromeda ride away together, with Bubo the owl flying beside them, as the film ends.

Quick, non-spoiler context

To win the right to marry his love, the beautiful princess Andromeda, and fulfil his destiny, half-God-half-mortal Perseus must complete various tasks including taming Pegasus, capturing Medusa's head and battling the feared Kraken.