While looking for the Marines near Aether, Samus's ship is damaged by severe lightning storms from the planet. Said storms have caused electromagnetic interference that prevented the Marines from communicating with the Federation. Samus finds the troops dead and surrounded by hive creatures called Splinters. Deceased Marines suddenly rise and attack her, apparently possessed, and she fights them off. Samus then encounters her evil doppelgänger, Dark Samus, for the first time, and Dark Samus jumps through a portal. Samus decides to follow her through it and into Dark Aether, where Samus is attacked by a group of dark creatures called Ing, who steal the weapons from Samus's suit before pushing her back through the portal. Upon returning to Aether, Samus learns that the Marines were attacked by Ing-possessed Splinters, and decides to enter a nearby alien temple structure to look for clues. When she reaches the structure, she meets U-Mos, the last remaining sentinel of the Luminoth, an alien race that have fought against the Ing. He tells Samus that after a meteor struck Aether, a strange energy emanating from it created another image of Aether called Dark Aether, which hosted a deadly and aggressive species called Ing. He also tells Samus that the Ing have taken the Light of Aether, an energy source for Aether that keeps the planet alive, and begs her to retrieve it.
Samus goes to three regions—the Agon Wastes, a parched, rocky, desert wasteland region; Torvus Bog, a drenched swamp area that houses a partially submerged hydrosubstation; and the Sanctuary Fortress, a highly advanced cliffside fortress built by the Luminoth filled with haywire robots that serves as the Ing hive in Dark
