Opening on a dim evening, we meet Agnes White, portrayed by Ashley Judd, a woman in her thirties residing in a dilapidated motel in rural Oklahoma. While smoking outside her room, she receives a series of silent phone calls that leave her unnerved. Suspecting that the calls are from her recently released ex-husband Jerry Goss (played by Harry Connick Jr.), with whom she has a restraining order, Agnes struggles to confirm her fears as the caller never speaks.
The following morning, Agnes discovers a flier for a body shop on her windshield, a curious sight as no other cars are adorned with them. Dismissing it, she heads to the grocery store for some supplies, where she is caught off-guard by a man reaching for a bottle, triggering a sense of unease. That night, Agnes works as a waitress at a local lesbian bar, where she shares a wry conversation with her close friend R.C. (Lynn Collins). R.C. explains she can't have Agnes over due to her relationship complications, but they agree to meet later at Agnes' motel.
When R.C. and Peter Evans (Michael Shannon) arrive at Agnes' motel room, the tension shifts as the three share drinks, indulging in casual intimacy and conversation. R.C. jokes about Peter possibly being a serial killer, while he remains predictably shy and awkward around Agnes. As the night progresses, Agnes and Peter find themselves alone as R.C. leaves, and they begin to explore their connection further.
Agnes offers Peter a place to stay for the night, and after some awkward conversation, they fall into a strange companionship, learning about each other's pasts. Peter hints at a troubled life, suggesting he has been alone for quite some time. In a moment of vulnerability, he confides that he is living "in-between places," subtly revealing his homelessness. After spending the night, things turn dark when Agnes' estranged husband, Jerry, unexpectedly enters the scene, sparking a violent confrontation that leaves Agnes shaken and injured.
Peter steps in to help Agnes, bandaging her wounds and sharing breakfast plans, while she opens up about her painful past involving the mysterious disappearance of her son, Lloyd. As their bond grows, fleeting desires intermingle with the grim realities they face. The two share a night of intimacy, but their solace is short-lived as Peter spirals into paranoia, convinced that unseen enemies are after him due to his past military experiences.
Chaos ensues as Peter attempts to rid himself and Agnes of the perceived threats, leading to strange and desperate actions in the constantly shifting atmosphere of the motel room. Tensions reach a boiling point when Jerry intrudes once more, escalating the situation as Peter's mental state deteriorates. Agnes is torn between the safety of her familiar life and the uncertain freedom that Peter represents.
As their story unfolds, Peter's paranoia reveals itself as a deeper conspiracy that suggests they've been ensnared in a sinister military experiment. In a frantic bid to escape the palpable threats, they cocoon themselves in a deluge of delusion, believing that the only way out is through self-destruction. This tumultuous relationship culminates in a tragic yet intense climax: Peter and Agnes embrace their fate, setting themselves ablaze in a literal and metaphorical act of liberation, leaving behind a burned-out motel room as a testament to their chaotic love and surreal existence.
