Danae got pregnant by Zeus with Perseus and the king found out and put them in a wooden chest and sent them off to sea. When they got to shore nice fisherman finds them and takes them to the king.
The king tells Perseus to fetch Medusa's head so he could marry his mother while he was gone hoping he would die. Little did Perseus know that the king wanted him dead.
Perseus goes to the Graeae to get the location of the gorgons so he would be able to chop off Medusa's head. On his way to them he gets a mirror shield, sandals with wings, a wallet that expands out to hold anything, a magical sword, and a cap of invisibility.
Perseus goes to the cave that the gorgons live in to chop Medusa's head off to bring back to the king. He first uses the sandals to get closer to her then uses the shield to reflect it back to her and then uses his sword to chop her head off.
The king agreed to let Perseus to marry his daughter if he killed the sea monster. He uses Medusa's head to kill a sea monster and free the princess named Andromeda in exchange to marry her.
On the way home Perseus realized that the king wanted him dead that's why he sent him to go get him Medusa's head. When he returned home he was married and seen the king trying to force his mother to marry him so Perseus uses Medusa's head to turn the king and his men to stone and freed his mother.