She sold her soul to the mysterious Count Rompre, who is either Satan or a maybe a vampire. Rompre summons her from her crypt to sing for him. D'Avril starts off looking the part of a 100 year old corpse, but soon freshens up.
Rompre has a new prospect, struggling American Jean Randall, and summons all his undead minions for a party. But Jean's boyfriend shows up and sets the place on fire, rescuing Jean, and dooming Rompre and the rest.
Her first name is not given, and it's not clear which female minion she is.