Perseus is going to kill Medusa and bring her head to his soon to be step-father (which by the way doesn't like him)
Polydectes, an evil king in the island of Seriphos, is madly in love with Danae and wants to marry her. But he wants nothing to do with her adult son, Perseus. So he tricks Perseus into doing a deadly mission -- bringing to him the head of the monster, Medusa.
So with that Athena gives Perseus a shiny bronze shield. Hermes a sword that cannot be bent by the Gorgon's scales, and the three nymphs gave him winged shoes, a cap to make him invisible, and a pouch to carry the Gorgon's head.
Perseus flew first to the home of the aged ones. These three women, who were sisters to the Gorgons, were born with gray hair and shared a single eye and tooth between them. Wearing his cap of invisibility, Perseus snatched the eye as one sister passed it to another. Threatening to keep the eye, Perseus coerced them into revealing the Gorgon's secret hiding place.
Perseus swiftly cut off Medusa's head and stored it in his pouch for later.
When Perseus returned to Seriphos, the heartless Polydectes laughed at him and asked what was in his sack. Perseus dragged out the horrifying head of Medusa and turned Polydectes to stone.