Calibos instead demands that she take vengeance on Joppa. At the wedding in Thetis' temple, Cassiopeia declares that Andromeda's beauty is greater than Thetis'; an earthquake starts, causing the head of the statue of Thetis to break off and crash to the floor. Thetis, using the statue's head to speak through, declares that Cassiopeia will pay for her boasting and for the injury inflicted on Calibos and demands Andromeda be sacrificed to the Kraken on pain of Joppa's destruction. Perseus seeks a way to defeat the Kraken. However, Pegasus is captured by Calibos and his men. Zeus commands Athena to give Perseus her owl Bubo, but she refuses. Instead, she orders Hephaestus to build a mechanical replica that leads Perseus, Andromeda, Ammon, Thallo and some soldiers 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 the gorgon Medusa, whose gaze can turn any living thing into stone. Medusa lives on an island in the River Styx at the edge of the Underworld. The next day, the group continues on their journey while Andromeda and Ammon return to Joppa. On the Gorgon's island, the three soldiers travelling with Perseus are killed. Perseus fights and kills Medusa's guardian, a two-headed dog named Dioskilos. At the Gorgon's lair, Perseus uses the reflective underside of his shield to deceive Medusa, decapitate her, and collect her head. However, 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's remaining escorts. Alone, Perseus overcomes the scorpions and kills Calibos. Weakened by his struggle, he sends Bubo to rescue Pegasus from Calibos' henchmen. After reaching the amphitheater in Joppa, Perseus collapses from exhaustion. Andromeda is shackled to the sacrificial rock outside Joppa, and the Kraken is summoned. Bubo distracts the beast until Perseus, whose strength was secretly restored by Zeus, appears on Pegasus. Using Medusa's head, Perseus petrifies the Kraken, causing it to crumble to pieces. He then tosses the head into the sea, frees Andromeda, and marries her. The gods predict that Perseus and Andromeda will live happily, rule wisely, and produce children, and Zeus forbids the other gods to pursue vengeance