Perseus arrived at the land of the Gorgons, where they were all sleeping. Unsure of which one was Medusa, Perseus received one final piece of advice from Athena. Which was that medusa's head was in the middle.
The Road Back
Perseus held the sword at his side, and approached Medusa in her sleep. He used the shield as a mirror just in case the gorgon woke up, as Perseus took off her head. But then the gorgon woke up.
The other gorgons tried to attack Perseus, but failed. This is because they could not find him since he was invisible. He now claimed Medusa's head to bring to Polycdectes, and head off home with Perseus's prize.
Return with Elixir
Perseus made his way home without Hermes as a guide and met a young princess named Andromeda. Then Perseus married Andromeda and returned to his original home with her. For a while, life was peaceful.
Perseus returned to Polycdetes and gifted him the severed head of Medusa. Polycdetes did not believe that Perseus had really slayed Medusa on his own. It was an impossible task to do alone.
Perseus returned to his true home with his mother and wife. One day, Polycdetes hosted a series of games, which Perseus participated in. Coincidentally, while playing discus, Perseus accidentally killed his grandfather, fulfilling the oracles's prophecy.