A familiy that was divided for many years gets together in a secluded house in the woods to try an extreme intervention in order to convince Justin (the younger son of the family) to leave a dangeroous cult that has turned him into a very violent person, and with a clear desdain for his family.
The task of getting back the person they knew as Justin is obviously not easy, even with the help of Jimmy, a former marine and a expert cult deprogrammer. After a very violent session, Jimmy warns the Powell family that although the damaged caused to Justin by the cult is very severe, they can still get him back, but they need to follow his instructions, no questions asked. This turns to be more complicated than expected since there is a lot of resentment among the family, specially towards the mother, who divorced her husband many years ago and left the family behind.
Justin, clearly mad about being abducted and brought to the house, claims to now go by the name of Thanatos, and that soon his new (and only) family will come to his rescue. He also lets the Powell know that everybody in the house, including the baby girl he just had with his girlfriend Samantha, will be sacrificed as punishment.