MS .45

While walking home from work, Thana, a mute seamstress in New York City's Garment District, is raped at gunpoint in an alley by a masked attacker. Returning to her apartment, she is raped a second time by a burglar. Thana strikes this second assailant with a small glass apple, then bludgeons him to death with an iron, before carrying his body to the bathtub. The next day at work, Thana goes into shock after watching her boss Albert rip a shirt off a mannequin, which worries her co-workers.

After being sent home, Thana dismembers the burglar's body, keeping his .45 caliber pistol. She places the pieces of the body into plastic garbage bags and stores them in her refrigerator. After cleaning her bathtub, she decides to take a shower, but as she strips, she hallucinates the first attacker in the mirror grabbing her breast, horrifying her. She also notices that organs and body fluids from the burglar are overflowing in the drain. Mrs. Nasone, Thana's nosy neighbor and landlady, begins to notice her odd behavior.

The next day, while disposing of one of the bagged body parts, Thana is noticed by a leering young man on the street. Thinking that she accidentally dropped the bag, he retrieves it, frightening her. He chases her through the alleys of the city and, fearing another sexual assault, she fatally shoots him when she is cornered by him. Following the incident, Mrs. Nasone spots Thana rushing up the stairs and throwing up. She insists on calling a doctor for Thana. Meanwhile, Mrs. Nasone's dog, Phil, starts to become attracted to her refrigerator. Thana escorts her out of her apartment while still in shock.

As the limbs start to attract the attention of the media, Albert brings Thana into his office and invites her to a Halloween party that he is throwing for work, telling her that there will be "many boys there [her] age" while stroking her neck. She responds to him in writing, saying, "I'll try." As her quest of vengeance increases, Thana starts regularly targeting and killing several men, including an arrogant fashion photographer, a pimp who assaults a prostitute, several members of a gang seeking to sexually assault her, and a Saudi Arabian businessman and his limousine driver. She pulls the gun on a recently dumped salesman she meets at a bar, but it jams; he grabs it from her, then unjams it and uses it to shoot himself in the head, committing suicide.

Albert notices Thana ditching work after going to lunch with her co-workers, resulting in her co-workers having to cover her share. She promises to go to the party with him in exchange for staying out of trouble for her absence. Thana notices that Phil is attracted to the smell of the burglar's severed parts, growing more interested after she grinds one of them into hamburger and feeds it to him. She takes Phil for a walk, leaves a note saying that Phil ran away but will probably find his way back home soon, then ties him to a post near the river and draws her gun on him.

Thana attends the costume party dressed as a nun in the company of the increasingly lecherous Albert. Mrs. Nasone enters Thana's apartment and finds the burglar's severed head. She assumes that Thana killed Phil and calls the police. At the party, Albert takes Thana upstairs in private and attempts to seduce her, and she shoots him. The people at the party hear the gunshot and run upstairs to Thana, but quickly realize that she is the murderer when she steps out of the room with her pistol. Thana begins a shooting spree, targeting the men present. Her co-worker Laurie picks up a nearby knife and stabs Thana in the back. Thana turns around and points the gun at Laurie, but hesitates; she screams out "Sister!" before she falls to the ground and dies.

Following the party massacre, the tearful Mrs. Nasone attends a memorial for her husband and her dog Phil, but back at the apartment, the still-alive Phil makes his way back home and scratches at her apartment door.

Thana's killing spree ultimately comes to an end when her co-workers, realizing the danger she poses, intervene at a Halloween party, leading to her final, violent confrontation.

The ending cements the film’s tragic arc: Thana’s descent from victim to avenger to a threat herself. Her fate underscores the destructive cost of unresolved trauma and the blurred lines between justice and madness in a city that offers little help or redemption.