In Metroid Fusion, interstellar bounty hunter Samus Aran is attacked by an X parasite while exploring the mysterious planet SR388. This organism is not only deadly, but it can mimic the abilities of any creature it infects — including Samus herself! Saved from the brink thanks to an infusion of Metroid DNA, the X parasite’s only natural predator, she soon discovers that the parasite has spread to the research station orbiting SR388….