When he finds a lost beagle in the hills behind his West Virginia home, Marty tries to hide it from his family and the dog's real owner, a mean-spirited man known to shoot deer out of season and to mistreat his dogs.

James, an agent of CHERUB, a top-secret organization staffed by highly-trained but ordinary looking teens, joins his young colleagues in investigating a radical animal protection group that believes it is fine to sacrifice one human to save the lives of many animals.