Madison is paralyzed by shocking visions of grisly murders, and her torment worsens as she discovers that these waking dreams are in fact terrifying realities.
Twenty-seven long years after the brutal Simion Research Hospital incident, abused Madison wakes up in a hospital in present-day Seattle. But with numbing visions of murder getting in the way of a normal life, more and more, Madison's obscure past emerges, baffling both herself and the local detectives. Are these explicitly violent killings figments of Madison's troubled imagination? Either way, someone, or better yet, something, links the past to the present, demanding closure and blood. Is the bogeyman real?—Nick Riganas
In 1993, Dr. Florence Weaver and her colleagues Victor Fields and John Gregory treat a psychiatric patient named Gabriel at Simion Research Hospital. Gabriel has special powers like controlling electricity and broadcasting his thoughts via speakers. One night, Gabriel turns violent and kills several staff members of the institution.
Twenty-eight years later, Madison Lake, a pregnant woman living in Seattle, returns home to her husband, Derek Mitchell, after her pregnancy causes her to feel ill at work. During an argument, Derek smashes Madison's head against a wall after which she locks herself in the bedroom and falls asleep. Madison later wakes up to find Derek's body after having a dream of a man entering their house and violently killing him. The killer, still being in the house, attacks Madison, rendering her unconscious.
The next morning, Madison wakes up in a hospital and is informed by her sister, Sydney, that her unborn baby didn't survive the attack. After being interviewed by police detective Kekoa Shaw and his partner Regina Moss, Madison returns home. That same hour, Gabriel kidnaps a woman running the Seattle Underground Tour. Madison sees another dream about Gabriel murdering Weaver.
During their investigation, Shaw and Moss discover a photo of Madison as a child in Weaver's house and learn that she specialized in child reconstructive surgery. Madison and her sister approach the police after watching Gabriel murder Fields. Gabriel contacts Madison, causing her to remember her past. She and her sister visit their mother, Jeanne, to learn more. Madison realizes that Gabriel wasn't her imaginary friend but someone real with whom she talked to during her childhood. Shaw finds a link between the doctors and Madison, which leads him to discover Gregory's dead body.
The detectives enlist the help of a psychiatric hypnotherapist, hoping to unlock Madison's memories. Madison recalls that her birth name is Emily May and that Gabriel wanted her to kill her unborn sister. She almost came close to doing it but was able to stop. The police arrest Madison when the kidnapped woman falls from the attic in her home, revealing that Gabriel was living inside her house. It is later revealed that the woman is Serena May, Madison's birth mother. Sydney visits the now locked Simion hospital and finds that Gabriel is Emily's twin brother, who lives inside her body as an extreme version of a "teratoma" sharing the same brain as Emily. Weaver operated on Emily to cut out the parasitic tumor and sewed Gabriel back into her brain. He was dormant during her childhood but woke up when Derek smashed her head in.
Gabriel, provoked by fellow inmates in the lockup, takes control of Madison's body, slaughters them and almost the entire precinct with superhuman strength and agility, eventually leaving with his clothing and weapon. Sydney and Shaw intercept him at the hospital where Serena is admitted. Shaw is severely wounded by Gabriel and Sydney is pinned to the wall by a thrown hospital bed. Sydney informs Madison that Gabriel is the cause of her miscarriages because he was feeding off her fetuses. Angry at the revelation, Madison wakes up and takes back control of her body. Transporting themselves to a black mindscape, Madison locks a disbelieving Gabriel behind bars saying that she is now the one in control and that Gabriel's powers are hers now.
As Madison leaves Gabriel to rot in the mindscape, he insists to her that he will return one day. Madison replies that she will be ready for him when he does and leaves the mindscape. Back in the hospital and in full control of her body, Madison lifts the hospital bed pinning Sydney to the wall with her newly acquired superhuman strength. The pair hug as Madison affirms that even though she was adopted and is not related by blood, she was her sister all along and proud to be so. As the two embrace, a light bulb in the corner of the room flickers slightly.
