I'm going to lock my only daughter Danae. So that she will never be able to have children or get marry.
Your grandson will kill you in the future.
But Zeus Had other plans he turned himself into gold. And a child began to grow in her. Months later she gave birth to Perseus. Acrisios locked the mom and the child into a chest and threw them into the sea. A fisherman found them and took them to King Polydectes.
When Perseus grew up, Polydectes gave him many hard tasks to complete. He had a sword made by the god Hermes, sandals, and a shiny bronze shield given to him by Athena. Perseus killed Medusa. The lady with snakes for hair, elephant like tusk for teeth, and blood red eyes. If you looked at her you would be turned into stone.
After many success, Perseus began to think about the stories about his grandfather. He set up to Argos. But when Acrisios heard that he was coming he fled the city. Since he was scared about the prophecy.
While waiting for Acrisios to return, Perseus went to a festival where he entered the discus contest. As he prepared to throw it he lost control and the disk flew into the crowd where it hit a man. The man was Acrisios.
Since Perseus was troubled about the accident he chose to leave the city and build his own city which was called Mycenae.