Once upon a time Acrisius was told that one day his grandson would kill him. He put Perseus and Danae in a chest at sea in hopes that would kill them, but the chest made it safely to an island. They were saved by a fisherman named Dictys.
After many years, Polydectes, the island's ruler, wants to marry Danae. Perseus goes in search of a gift and wants to bring back Medusa's head.
Hermes told Perseus to steal the Gray Women's eye until they tell him how to get to the Nymphs of the North, which they do.
Hermes gave Perseus an unbreakable sword. Athena gave him her bronze shield to use as a mirror so he wouldn't turn into stone by looking at Medusa.
He also received winged sandals to fly over medusa, a magic wallet to hold her head, and a cap that made him invisible.
After killing Medusa, Perseus presented Polydectes with her head. Upon looking at the head, Polydectes and his men turned to stone.
Perseus participated in a discus throw, the discus ended up landing on Acrisius which killed him much like the prophecy had said.