All three Gorgons were sleeping when Perseus entered their cave. Rather than risking his death by looking directly in the Medusa's face, he beheaded her by using his divine shield as a mirror. He quickly stowed the severed head in a bag as proof of his conquest for Polydectes. The other two Gorgons awoke and chased Perseus but the Medusa's magical blood transformed into the mythic horse Pegasus and on his winged back, he escaped.
During the return to Seriphos, Perseus stopped in the kingdom of Ethiopia. Queen Cassiopaeia had brought a curse on the kingdom by bragging that she was equal in beauty to the goddess Aphrodite. Aphrodite punished the kingdom by sending a treacherous sea serpent. An oracle told Cassiopaeia, in order to save the kingdom, she must chain her daughter Andromeda to a rock at sea for the monster to devour.
With the help of Pegasus, Perseus battled the sea serpent and won. He then freed Andromeda and claimed her as his bride. However, she was already betrothed to Phineus. At the wedding, a quarrel broke out between the two men and Perseus unveiled the Medusa, turning his rival into stone.
Ultimately Perseus returned to his homeland of Seriphos. When he arrived, he learned that Polydectes was pursuing his mother so violently that she had gone into hiding. Perseus then killed the king with the head of the Medusa.