The Blue Lady was a sirine that was transmuted by the Spellplague. Twisted, she resided in Tohrepur. There, prior to 1473 DR, she transformed the farmer Khault, who was fleeing from his destroyed village, into an aberration and he gathered a cult around her.
In 1479 DR, Khault sent members to Airspur to recruit. The Choir kidnapped several residents of Airspur, including the twin sister of a genasi named Ghaelya who the cult believed to be a prophetess. With the help of Uthalion and a few of his friends, Ghaelya traveled to Tohrepur, where one of her friends killed Khault and destroyed the Blue Lady.