After almost drowning in a lake, Madison finds herself bound to a life of fear. Unable to describe what happened to her during the moments she was underwater, she begins to develop hydrophobia: an abnormal fear of water. Crippled by her post trauma, Madison attempts to shut out the world but her fear intensifies and she is faced with the vision of a dark figure that haunts her day and night. After watching her struggle for one year with the phobia and visions, Madison's four friends attempt an unconventional intervention in which they accidentally open a floodgate to a dark place where none of them are safe. As Madison and her friends dive deeper into the dark history of this figure that haunts them, it reaches out and begins dragging them to a horrifying place that they can never come back from.

Siblings, Brad and Lisa Carpenter, along with two lifelong family friends, Will and Vanessa, set out road-tripping to an annual family reunion. They make the decision to find a place to stop and camp for the night. What ensues is a violent disturbance by six masked assailants, without motive or reason. The group find themselves living a night of psychological games and physical terror, and as morning dawns; the reality of what will come is more terrifying than anything the group could have ever imagined.