She offered pastries for free to the injured The Pack in Curse Of Strahd. These same adventurers later found her secrets after encountering the Keepers of the Feather while investigating her further, not trusting her disguise. Laszlo Lazarescu warned the party against facing her Morgantha and her daughters head on; knowing they were outmatched against a coven, the party skirted the windmill to go to Vallaki, swearing that they would one day return.
The Pack eventually did so to save Tessa Nicoleva, whom Bella had purchased from her addicted parents. They raided the windmill and slayed both of Morgantha's daughters. Unable to mount a resistance with her coven destroyed, the night hag disappeared to the Ethereal Border, but was sent messages by Atlas Atruvian warning her to stay away from The Pack, or they would kill her as well.
Swearing a vow of revenge, Morgantha trekked to Castle Ravenloft to appeal to the dread lord Strahd von Zarovich, remaining in the Ethereal plane to ensure her safety. Before she reached the castle, however, she was assassinated by the Ghost of Tasha Petrovna, invoked by Ghalwin Forrester.