Eve of destruction

"Class is in session, but Evangeline Hollis is far from being the star pupil. She's struggling to get through the required training to be a full-fledged Mark--one of thousands of sinners forced to hunt demons for God. When her class goes on a weeklong field trip to an abandoned military base, passing the course suddenly isn't just a matter of pride...it's a matter of life and death. There's a demon hidden amoung them, killing off Eve's Classmates one by one."--Publisher's discription.