When you're learning to hunt demons, homework can be hell... Class is in, 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 week-long 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. As the body count rises, a ragtag team of ghost hunters from a cable TV program unwittingly stumbles into the carnage. Now keeping the Mark system secret competes with the need to keep the "paranormal researchers" alive. With Cain on assignment and Abel investigating a new, terrifying class of demon, Eve must fly solo on her hunt to stop a killer before he strikes again.