Danae had a baby and the Oracle at Delphi told Acrisius that this child would kill him one day so Acrisius put Denae and the child in a wooden chamber and set them to sea.They were found by Dictys at the island of Seriphus
Polydectes was the king of the island and he had fallen inlove with Danae,and wanted to marry her but her son perseus was going to be trouble for him.So Polydectes came up with a plan to send Perseus to get the head of Mudusa the Gorgon
Perseus go's to Graeae ans steals there eye making temporarily blind and keeps it until they give him the information he is looking for.
he reached the cave of the gorgons they were asleep .He flew over to Mudusa and Guided by her reflection in his mirrored sheild,and used the sword to cut off her head before she woke up.
On his way back home he passed Joppa where he saw Andomeda ,a beautiful princess chained to a rock.her mother had offended the sea-godesses and Poesidon sent a sea monster to devour the whole city unless the king would sacrifice his daughter.Perseus had fallen in love with her and wanted to marry her so Perseus showed the sea monster Madusas head and turned him into stone
Many years later ,Perseus was participating in a discus throwing contest. He accidentally flung the discus into the crowd and killed a spectator,who is, unbeknownst to him , Acrisius ,his grandfather .The original prophecy had been fulfilled .