Pirates have captured an alien life form known as Metroid, which was responsible for the destruction of an entire planet, SR388. . It's up to you to prevent the Mother Brain that controls Zebes from using the Metroid for evil purposes. But that won't be easy. This is where you, Samus Aran, bounty hunter par excellence come in. Your mission is to stop the pirates and capture the Metroid. If you survive, it will be you and your acquired powers against the Mother Brain.