Malphus has control of Amy, but with Holyoke's help, Jessie, Garrett, and Alex attempt to rid Amy of the possession and stop Malphus for good. But once Holyoke attempts to play the hymn that will purify Stillwater, evil spirits disintegrate him instead of spirits of light. The piano he used had been turned into an evil vessel since the last time he used it.
Meanwhile, Deb, Blair, and Drew attempt to save the kids and get away from Camp Stillwater, but when a spirit stops them by blinding the bus with blood, the driver is killed, and Deb leaves the bus to be the kids' savior. But, after the kids are saved, Deb herself loses her life ot Malphus and his helper.
His helper being Amy, who was never really possessed in the first place. She invited him, she killed Blotter, Cricket, Joel, everyone, all of her own accord. After feeling trapped her entire life, she killed her parents and brother, her friend that we thought fell off of the roof when actually Amy let go of her, and she came to Camp Stillwater feeling drawn to the demon inside of the lake.
If only they'd listened to Holyoke and killed her.