The falling action of the Gorgon's Head is when Perseus successfully killed Medusa and had her head with the snaky locks. He later return back home where he presented to the cruel that he was successful in taking Medusa's head. He showed Medusa's head to the entire people of the kingdom including the king that leads them to become cold and lifeless statues as they stare directly to the snakes situated on Medusa's head. He did that because the king was very cruel and so are his people.
