Father Tomas and partner Marcus Keane discover a new malevolent presence at a home for at-risk foster children.
Tomas and Marcus attempt to escape Cindy's enraged family, while simultaneously trying to finish her exorcism; Rose is concerned about Caleb's mental state; Andy's neighbors offer to teach the children farming skills; Verity may be hiding something.
Andy tries to help his foster daughter overcome her agoraphobia; Marcus and Tomas travel to Seattle, where they encounter a new possession case; Father Bennett tracks down a rogue church operative.
As Andy confronts the strange incidents taking place on the island, his foster home receives a surprising new addition; Marcus investigates a series of natural disturbances with the help of a local wildlife biologist.
The demon finally makes its presence known; the two priests must race to find evidence of possession before it is too late; Andy and Rose take the children on an overnight camping trip; disturbing new information about the conspiracy comes to light.
A visit to the foster home carries deadly consequences; Marcus and the Rev. Tomas attempt to draw the demon out; Rose is targeted by the demon's wrath; the Rev. Bennett and Mouse search for an old adversary.
As the exorcism begins, the fate of the foster home hangs in the balance; Marcus and Tomas are tested to their limits.
Father Bennett and Mouse head west to meet Marcus and Tomas; with time running out to finish the exorcism, one of the foster children faces a difficult choice.
The exorcism reaches a critical juncture; Tomas battles to save Andy's soul; Marcus and Rose try to get the foster children off the island; a storm descends upon the island; salvation may come from an unlikely source.
The exorcists must make the ultimate sacrifice to save Andy's life.