In order to find the Nymphs, he had to ask the sisters where they were. Perseus took their only eye, and threatened to squeeze it if they don’t tell him where the Nymphs are. Finally, they crack.
Perseus flew west until he found the Nymphs. The Nymphs try to dance with him and play with him, but he was determined to solve his quest. The Nymphs finally told him where the Gorgon sisters are, not before making him promise that he will visit them.
With the shoes from Hermes, he flew to the Gorgon sisters to get the king the head of Medusa. He did not use his shield for something to block with, instead he used the reflection of the shield to watch out for Medusa, since he couldn’t look directly at her, or he would turn to stone. Perseus kills her, and packs up her head.
On his way back, he finds a princess being sacrificed for Poseidon. He kills the monster that was tormenting the village, and saves the princess. He later insists that he will take her as his bride. Now he can finally go home.
Perseus arrives back home and finds that the village is abondonded, so he looks for his mother and finds her covered in jewels. He tells his mother to close her eyes, and freezes everyone in the room, including his grandfather. This is how he fulfilled the prophecy that he would kill him. He saves his mother.