In the unsettling world of phrogging, where individuals secretly reside in occupied homes, teenagers Mindy and Alec discreetly enter the suburban abode of police detective Greg Harper, his wife Jackie, and their teenage son Connor. Despite Mindy's insistence on remaining inconspicuous, Alec's psychological torment escalates into chaos as he disrupts the Harpers' lives—removing family photographs, turning on televisions, and even urinating on Greg as he sleeps. He mischievously hides Jackie's cherished sunflower mug, leading the family to speculate about a possible paranormal intruder.
As tensions rise, Connor and Greg grapple with the emotional fallout of Jackie's affair, causing Greg to express his frustration by hurling his phone through a window. This incident invites a repairman to their home while the family is away, and unbeknownst to Mindy, Alec urges her to let him in. The situation spirals as Jackie unexpectedly returns and is taken aback to find an unknown man in her house, particularly after discovering that her silverware has vanished—an act of mischief initiated by Alec.
Lieutenant Moriah Davis assigns Greg and his partner Ray Spitzky to investigate the baffling disappearances of Michael King and 12-year-old Justin Whitter, the latter of whom inexplicably vanished while biking through the woods. During their investigation, they stumble upon a green pocketknife at the scene, reminiscent of those used by notorious convict Cole Gordon.
As they pursue leads, they seek out Tommy Braun, one of Gordon's surviving victims. Haunted by horrific memories, Tommy reveals the existence of a magic house that fades away. His cryptic warning captivates Spitzky, who learns of the dire consequences connected to their quest. Meanwhile, Jackie's lover Todd comes to the house seeking her affection. In a cruel twist, Alec throws the sunflower mug at Todd, mistakenly believed to be a product of Connor's jealousy.
The situation spirals out of control as Jackie discovers Todd’s lifeless body in their basement after a traumatic confrontation with Greg, who felt compelled to protect his family from the chaos. In a panic, they decide to bury Todd's body in the woods, with Connor unwittingly discovering the hidden silverware, which sets off a chain reaction of disturbing realizations.
In a shocking turn of events, Connor receives a cryptic text about "phrogging" and stumbles upon Alec, who captures him while wearing a frog mask. A terrifying struggle ensues as Mindy realizes Alec's descent into darkness. Confronted by the chilling reality, she suffers a brutal blow, rendering her unconscious and whisked away in Greg's vehicle. Awaking in a hazardous situation, she flees into the woods, only to witness the unfolding horror.
Mindy soon uncovers a hidden trailer wherein Michael and Justin are trapped. As she attempts to rescue them, she is violently ambushed by Greg, who suffocates her, leaving a trail of deception in his wake. Upon returning home, Greg stages a fatal encounter to frame Mindy while searching for Alec.
In the gripping climax, Alec confronts Greg armed with an axe after cleverly luring him downstairs. Their struggle culminates in tragedy as Greg succumbs, followed by an unforeseen intervention from Spitzky, leading to an explosive resolution that reveals Alec's true motivations and haunting history with Greg.
As police rescue the two imprisoned boys, Mindy’s final moments flash vividly in Alec's mind, capturing the heart-wrenching childhood tie to a sinister past that refuses to remain buried.
