The Frontier

Laine, a drifter, sleeps in her car parked at the motel. She hides a personalized money clip before meeting the owner, Luanne. Luanne serves her a free meal and begins to form a plan to hire her.

Police officer Gault explains a brutal murder in nearby Flagstaff as he changes Laine's flat tire. He hints at danger and a larger scheme tied to the case. As a favor for Luanne, Laine fixes Gault a coffee.

On Gault's suggestion, Luanne offers Laine a job as a motel diner waitress. Laine initially declines the job and asks for a free room for the night instead. Luanne agrees to provide a room, hoping to secure her cooperation.

Before going to sleep, Laine sneaks into an adjoining room to snoop. She steals a necklace and a bottle of sedatives, then overhears the couple discussing a completed heist. The overheard plan plants the seeds for the looming scheme.

Laine apologizes for the earlier trouble and asks for the job again. Luanne hires her, promising a chance to leave an abusive boyfriend behind. The arrangement marks Laine's entry into the motel's circle of guests and schemes.

In the diner, Laine meets the guests: Lee, Flynn, Gloria, and Eddie. When Gloria announces her necklace is missing, the others scramble to calm her while Gault watches. Laine slips away and returns the necklace, and Gault flirts with her, only to have her rebuff him; he retaliates by slashing her tires.

Laine practices slipping sedatives into a drink by knocking out a customer. Later, Flynn and Gloria celebrate their supposed fortune and drink, while Laine tries to spike their drinks. Lee returns, confronts Laine and beats her, demanding to know who she really is.

Lee returns and confronts Laine, beating her and demanding her real identity. He relents only after Laine admits to killing a man in Flagstaff who tried to rape her. Lee recognizes the money clip as belonging to the murdered politician, and after Luanne convinces him, he agrees to let Laine live and include her in a share of the heist.

All return to the diner, and Laine serves coffee spiked with sedatives. Eddie declines to drink and receives a smaller dose from the alcohol Laine previously drugged. Gault briefly returns and flirts with Laine before leaving, while a courier delivers the money and Laine tries to flee.

The courier delivers the money to the diner, but Eddie wakes, knocks Laine unconscious, and escapes with the cash. Laine accuses Eddie of drugging them and running off with the money, while Lee urges pursuit to recover it.

They find Eddie's car overturned and follow bloody tracks to a confrontation. Lee shoots Eddie and Gloria when Gloria tries to defend her brother, killing both of them. Luanne eagerly grabs Gloria's necklace and puts it on.

In the diner, the bodies are moved into the trunk and the group discovers the courier's body, leading them to suspect Eddie's involvement. Flynn shoots Lee and attacks Luanne, while Laine retrieves Lee's pistol and weighs using it. Luanne takes the pistol and kills Flynn.

Laine bludgeons Luanne to death with the sedatives bottle. Gault returns, calls for backup, and says the money was not recovered. Privately, he hints he may have been behind the Eddie corpse and lets Laine leave if she corroborates his version.

Gault allows Laine to leave, but only if she corroborates his version of the events. She steps out toward the road, wary of how closely she is now bound to his investigation.