For Evangeline Hollis, a scorching one-night stand has led to a divine punishment: the Mark of Cain. Now reunited, Eve and Cain are working on transitioning their insatiable desire into a tentative new relationship even as she struggles to become a full-fledged Mark, one of thousands of sinners forced to hunt demons as penance. When her training class goes on a field trip to an abandoned military base, things take a dark turn: there's a demon hidden among them, killing off Eve's classmates one by one. Eve's body is still adapting to the Mark and the new abilities and challenges that came with it, such as uncontrollable bloodlust ... which seems to be inciting another kind of lust altogether ... and with Cain out on assignment, his equally sexy brother Abel is more than willing to take the heat ...