Commander Shepard meets Falere on Lesuss while investigating a distress signal. She is saved by Shepard's squad or Samara (if she is present) from a Cannibal. Falere explains to Shepard that the Reapers are trying to turn all of the Ardat-Yakshi into Banshees. She begs Shepard to save her sister, Rila, from the monastery's Great Hall. However, when Shepard tells her about the bomb intended to destroy the monastery, she grows angry and accuses the Commander of not trying to help people. Despite the others' protests, Falere rushes on ahead to save her sister by herself.
Later, in the Great Hall, Falere is attacked by Rila, who has begun to suffer the effects of indoctrination. Fortunately, Rila is able to fight the Reapers' control and finds the bomb's detonator, insisting that Falere leave with Shepard while she stays behind and sets off the bomb. Falere struggles, but is dragged by Shepard to an elevator. Rila is attacked by several Banshees, one of which picks her up and mortally wounds her. In a final show of strength, Rila declares that the Ardat-Yakshi are not the Reapers' slaves and triggers the detonator. Once she makes it outside, Falere is distraught with Shepard for allowing Rila to die.
If Samara is present, she attempts to commit suicide so as to not to break the Justicar code which requires her to kill her last living daughter, Falere. If she is stopped, Falere declares she will stay in the monastery, and Samara joins the war effort. If Samara does not survive, Shepard can either let Falere stay on the planet, where she promises that she will not let herself be captured alive if the Reapers come again, or kill her, saying she is a risk.