King Acrisius knew that his daughter needed a husband however he feared that her husband would steal the throne from him. A prophecy told him that hid daughter will have a son that will one day kill him.
After hearing what the prophecy told him he locked hos daughter in a tower where she could not leave and nobody could get to her.
he has not heard that Danae has died so he goes to see her in the tower and finds out that she has had a baby and names it Avenger/Perseus.
King Acrisius sent his daughter and her son on a boat. They ended up on and island and a nice fisherman took them in and cared for them.
Perseus grew up on the island but the king of the island did not like him because he wanted to marry Danae and get rid of Perseus.
King polydectus and a princess of another island get married and everyone brings them gifts except Perseus because he does not have anything so he say he will get the head of Medusa.