Acrisius put Danae and Perseus into a wooden chest that he put on the sea, in fear that Perseus would kill him
King Polydectes tricked Perseus into promising to get Medusa's head. It is an impossible task that will almost get Perseus killed.
When Perseus got to the gorgons, he used the winged shoes to fly near Medusa, and he was guided by her reflection in the mirrored shield
From Medusa's neck, Pegasus was born. He was able to put Medusa's head in the expandable wallet. The two other gorgons woke up and started chasing him, but they couldn't see him because he was wearing the cap of invisibility.
Perseus spotted Andromeda tied up to a rock, and he offered to kill the sea serpent if he was allowed to marry her. Her father agreed, and Perseus show the sea serpent Medusa's head and turned it into stone
When Perseus got back home, he found Danae caged up at the altar, and King Polydectes was waiting for Danae to agree to marry him or died from starvation.