Note: This entire film unfolds in real time, shot with a single camera to resemble a continuous, unbroken performance akin to a one-act play.
In a chilling exploration of intellectualism taken to dark extremes, two exceptionally clever young men, Brandon Shaw and Phillip Morgan, commit an unspeakable act in their New York City apartment. Having grown restless from their privileged existence, they decide to murder their former Harvard classmate, David Kentley, as a way to enact the "perfect murder" and prove their superiority. The act becomes macabre, as Phillip tightens a rope around David’s neck while Brandon holds him down.
Once the gruesome task is done and David’s body is nestled within a sizable antique wooden chest, the duo prepares for a seemingly innocent dinner party with a stunning view of Manhattan’s skyline. In a twisted display of arrogance, Brandon chooses to repurpose the chest as a buffet table. When their housekeeper, Mrs. Wilson, arrives to assist in the preparations, Brandon chillingly remarks, >“Now the fun begins,” as the first guests make their entrance.
The unsuspecting guests include David’s fiancée, Janet Walker, and her former paramour Kenneth Lawrence, alongside David's distraught father, Mr. Kentley, and his chatty aunt, Mrs. Atwater, with David's mother absent due to illness. Unbeknownst to them, the trio’s malevolent scheme is intricately linked to years of discussions with their former housemaster, Rupert Cadell, who had instilled in them the toxic ideas of Nietzsche's concept of the Übermensch and the art of murder as a form of dominance.
As the evening progresses, Brandon's veiled references to David's absence incite an unsettling conversation around the intricacies of murder itself. Portraying an air of confidence, Brandon appears composed; however, he cannot disguise his increasingly erratic behavior around Rupert, whose mere presence is enough to unsettle Phillip, causing him to indulge in excessive drinking. The tension mounts as David’s absence becomes a focal point of concern for the other guests. Phillip’s unease reaches a peak when Mrs. Atwater, who fancies herself a seer, hints at his hands bringing him "great fame," deepening his paranoia.
As the night unfolds, doubt begins to surface along with questioning from Rupert that draws attention to inconsistencies. Phillip's nervousness about past statements, particularly about strangling animals, adds to the unraveling facade. When David’s father and fiancée express distress over his prolonged absence, Brandon stirs the pot further by playing matchmaker between Janet and Kenneth, only increasing the tension.
Amid the chaos, an urgent call from David's mother creates a sense of palpable fear, prompting more guests to leave. With a twist of fate, Mrs. Wilson inadvertently hands Rupert David’s hat, which heightens his suspicion. Once the party concludes, Brandon and Phillip breathe a sigh of relief, thinking they can dispose of the body unnoticed.
However, Rupert soon returns, claiming he forgot his cigarette case. His inquiries turn into piercing scrutiny of the events of the evening. As the atmosphere grows tenser, Phillip, overwhelmed, lashes out, leading to a struggle for Brandon’s gun. In a chaotic moment, the gun goes off, grazing Rupert, but the grim discovery follows as he uncovers David's corpse hidden within the chest.
Horrified, Rupert confronts the implications of their actions, recognizing the moral implications of his past teachings. He denounces the ideology of superiority he once espoused and, in a moment of desperation, fires several shots out the window to summon the police. As the sounds of sirens grow louder, Rupert takes a seat next to the chest, while Brandon nonchalantly pours himself a drink. In a devastating close, Phillip begins to play the piano one last time, as the screen fades to black, and the end credits roll.
