Katie (Jemma Dallender) is an aspiring model from Missouri who works as a waitress in a New York City restaurant. Desperate to update her portfolio, she calls an ad which advertises free professional photos. She then meets three Bulgarian siblings; Ivan (Joe Absolom), appears as a photographer, and his brothers Nikolai (Aleksandar Aleksiev) and Georgy (Yavor Baharoff), as assistants. Georgy is seemingly infatuated with Katie, and she leaves after disagreeing with Ivan about her taking a topless shot. Later, Georgy arrives at Katie's apartment and proceeds to bind, gag, and anally rape her. Katie's neighbor, Jayson (Michael Dixon), arrives and tries to stop the rape but is stabbed, leaving him to witness Katie's ordeals before he dies. Katie is force-fed ketamine by Georgy after his brothers arrive and renders her unconscious.When she awakes, she finds herself stripped naked and handcuffed to a pipe and lying on a dirty mattress in an old basement. She is gang raped and tortured relentlessly by the three brothers. When she manages to overpower Georgy and escape from the building, she finds herself that she has been abducted to the rapists' home country and is in Sofia, Bulgaria. Katie goes to the nearest police station to give a statement. Detective Kiril (Georgi Zlatarev) hands Jennifer over to Ana (Mary Stockley), a woman who claims to be from a rape crisis center. Katie tells Ana to go to American embassy but instead, is not embassy she wanted to go but the house of Ana where Katie was sadistically tortured by the men. Ana turns out to be Nikolai and Georgy's mother, and takes pleasure of Katie's ordeals. Katie is returned to the basement and solicited to Valko (Peter Silverleaf), who was one of the family's late-patriarch's friends. Valko tasers her genitals then rapes her, leaving her bloodied afterward. Ivan then comes down and beats Katie.Katie is placed in a box and buried alive along with Valko's taser and her crucifix necklace, but the ground the coffin is on breaks and she falls into the sewers below. Naked and with nothing to eat, Katie begins stealing from a nearby church and is eventually caught by Father Dimov (Valentine Pelka), who recognizes that she's a rape victim. He allows her to take food and clothing, and offers her a Bible.Katie is next seen outside the U.S Embassy, but leaves before going in. Later, she returns to the church and Dimov tells her that he knows she has been raped and offer supports. Katie goes back to the sewers, leaving her Bible open to where Dimov can read. After reading a scripture, Dimov realizes that Katie seeks revenge against her rapists.Katie plans her attempt by first sneaking into and stealing money from Ana's house, using them to purchase clothes, weapons, and supplies. She places her crucifix in Georgy's coffee at a café afterwards. Katie lures Georgy into the sewers, where she captures him around the neck and then hangs him by his arms on the wall. She brutally tortures Georgy with a pocket knife, smearing fecal matter into his wounds to set infection in, then leaving him to die slow and painfully as he did to Jayson.Meanwhile, Father Dimov has contacted Detective Kiril, who realizes that Katie is still in trouble. Both men seek to save Katie from herself, in addition to help her see that justice would be served.At a nightclub that evening, Katie laces Nikolai's drink with ecstasy and he runs to the bathroom, where she violently drowns him in a toilet full of urine and then into feces.The next day, during a congregation, Valko sees Katie lurking about. He chases after her through the door into the basement where Katie strikes him with a rock. When he regains consciousness, he is strapped to a bed and is tased in his genitals as he had done to her before putting a cable on his mouth. She ultimately electrocutes him to death by sending a powerful current of electricity through the cable.Ana finds her house has been burglarized and Katie pushes her through the fallen ground into the sewers. Ana is bound in a box and forced to watch while Georgy dies. Ivan sees the opened ground thus realizing that Katie is still alive and has escaped, but he is later captured by her and tied to a table. Katie then tortures Ivan by having his testicles crushed.Elsewhere, Kiril hears Ivan and Ana's screams and follows them to the sewers. During the tortures, Ivan reveals that Ana is his stepmother, who herself was Ivan's late-father's victim before marrying her rapist. Nikolai and Georgy were products of Ana's rapes. Katie realizes Ana's sadistic nature, thus lacking any morality or conscience. Kiril arrives and holds his gun up to Katie when she's about to kill them both, who is then suddenly grabbed and strangled by Ivan. Kiril shoots Ivan in the head and lets Katie leave. Ana is left as the sole survivor, leaving her to be arrested by Kiril for her part in her family's crimes.In the final shot, Katie arrives at the US embassy and walks towards it before the screen cuts to black.