When his estranged brother, Pastor Paul, makes the two hour trip into Riverton to ask for Detective Lieutenant Matt Warner's help after finding a dead dog on his property, Matt agrees to at least look at the animal. Matt is intrigued by the strange circumstances he finds and takes the carcass to a local vet for a necropsy. The trail leads into a web of a questionable suicide, stories of devil worship, witches, curses, human sacrifice; and a Catholic priest who will only tell Matt that he must come to terms with what he believes in order to face a 'most formidable foe.' The deeper Matt digs into the cult next door to his brother, the more dangerous it becomes and several attacks take place - first on Matt's house, then on Matt alone, and finally on Matt and his girlfriend Cassie while together. Undaunted, Matt and Paul set out to gather evidence, only to be captured, and the old priest's warning becomes a reality - Matt must come to terms with what he believes as he faces 'a formidable foe' and the truth about his own past.