Eve of destruction

"Class is in, but Evangeline Hollis is struggling to get through the requisite training to be a full-fledged Mark. When her class goes on a field trip to an abandoned military base, passing the course isn't just a matter of pride. It's a matter of life and death. There's a demon hidden among them, killing off Eve's classmates one by one. With Cain on assignment and Abel on an investigation, Eve must fly solo on her hunt to stop a killer before he strikes again."
""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 among them, killing off Eve's Classmates one by one."--Publisher's discription."@en
"Class is in, but Evangeline Hollis is struggling to get through the requisite training to be a full-fledged Mark. When her class goes on a field trip to an abandoned military base, passing the course isn't just a matter of pride...it's a matter of life and death. There's a demon hidden among them, killing off Eve's classmates one by one. As the body count mounts, a ragtag team of cable TV ghost hunters unwittingly stumbles into the carnage..."