On the night of December 27, 1945, a group of military veterans and lifelong friends gather at the home of their esteemed commander, Clive "Hock" Hockstatter (Larry Fessenden), in Park Slope, New York, to enjoy some cocktails. This reunion includes Marla Sheridan (Anne Ramsay), her husband Bob (Ron E. Rains), as well as Archibald "Archie" Stanton (Jeremy S. Holm) and Paul DiFranco (Ezra Buzzington).
While the friends reminisce, Hock is burdened by the recent suicide of his mentally ill wife, Susan (Lucy Carapetyan), who tragically took her life after no one believed her claims that their German neighbor, Hildegard (Kristina Klebe), was spying for Hitler. In a moment of grief, Hock reveals his fading belief in organized religion, resorting to spiritualism for solace. He persuades his friends to partake in an unexpected séance in a desperate hope to reach out to Susan.
The séance reveals itself to be a shocking success, with candles igniting, a closet door banging, and Susan’s ectoplasmic arm emerging as the music of Louis Jordan blasts from the radio. In a moment of desperation, Hock breaks the circle and reaches out, causing Susan's spirit to recede. Overwhelmed by the occurrence and grappling with the reality of an afterlife, Hock shockingly pulls out a pistol and takes his own life.
Amidst the chaos, the closet bursts open, revealing Hildegard, bound and gagged. As she breaks free, the friends question her identity and motives, resulting in tension and suspicion amongst the group. Archie reveals he's committed a war crime, while Marla showcases an unexpected brutality during her interrogation of Hildegard, much to Bob's astonishment.
Realizing they are trapped in the room by mystical forces, Marla believes the only escape is to finish the séance. As Hock's spirit possesses his lifeless body, he demands that the group kill Hildegard to secure their freedom. The situation escalates when Susan's ghost appears, accusing Hildegard of her murder. The revelations send Archie into a panic, forcing him to confront his horrific past.
In a frenzy, Hock's possessed body becomes increasingly violent, leading to a series of betrayals and tragic events. Bob, now wielding the gun, shoots at Paul in self-defense before turning the weapon on Hildegard, killing her amid the turmoil. Bob, feeling compelled to act for survival's sake, drops the gun, shaken by the horrors that unfolded.
Upon fulfilling Hock's malevolent demand, the parlor doors finally swing open. Bob, Marla, and Archie exit, but not without the weight of their shared trauma. Archie, grappling with his own guilt, decides to turn himself in. As Bob and Marla sit in their car, the emotional toll of the night engulfs them, ending with them overwhelmed in silence and tears, processing the grim events they just endured.
