In 1972, two priests were summoned to document a peculiar event in Jerusalem. It was disclosed that a collaboration of Jewish, Muslim, and Christian priests had been gathered to perform an exorcism on a woman who was believed to have died three days prior. Her son recounts how she initially appeared calm but later became violent, harming her husband in the process. After numerous failed attempts to heal her, the priests reach a harrowing decision—to take her life. In a desperate climactic moment, the woman screams and sprouts leather wings just as a priest fatally shoots her with a derringer.
Fast forward to the present day, and we meet two Jewish Americans, Rachel Klein and Sarah Pullman, who are excitedly planning a trip to Tel Aviv, Israel. During their flight, they encounter a student named Kevin Reed, who has a keen interest in religious mythology, particularly surrounding dark angels, the Golem, and the undead. Captivated by his enthusiasm, Rachel and Sarah agree to accompany Kevin on his pilgrimage to Jerusalem, where he intends to spend Yom Kippur.
As they arrive, they meet a local man who claims to be King David and warns them about the dangers lurking in the city. Dismissing his caution as madness, they check into a hotel. Rachel soon embarks on a romantic affair with a local Palestinian named Omar (Tom Grazian), while Kevin and Sarah’s connection deepens. The group revels in their time together, exploring Jerusalem’s vibrant social scene.
Their adventures take them to the Western Wall, where Sarah makes a heartfelt wish for her recently deceased brother, Joel, to return. Almost immediately, a flock of ominous black birds takes flight over the wall. Their trek continues to Solomon's Quarries, where Kevin is disturbed by strange drawings on the walls, prompting him to dig deeper into the city’s history. As he and Sarah investigate, Rachel and Omar remain behind. Kevin, sensing something amiss, warns Sarah to leave the city, insisting that tomorrow may never come, but Rachel hesitates to abandon their journey.
Despite Kevin’s concerns, Omar and his father dismiss his warnings, ultimately leading to Kevin’s confinement in a mental asylum. Later that night, Sarah witnesses military aircraft attacking sections of the city, with media reporting a potential terrorist threat urging residents to flee. Sarah decides to break Kevin out, but Rachel and Omar, accompanied by two Israeli soldiers, are determined to keep moving. Convincing the soldiers to assist her, Sarah manages to rescue Kevin, but when they regroup at the city walls, they discover it's under quarantine, and anyone attempting to leave is met with lethal force.
Unwilling to give in, the group considers an escape route through underwater caves that Omar remembers from childhood. As they progress, they encounter terrifying demons that horrifically assault civilians, infecting and devouring them. Kevin theorizes that the gates of hell have been opened. In a devastating turn, Rachel begins to show signs of infection, prompting Kevin to caution Sarah that Rachel's condition could spread.
As they venture into the caves, Rachel's state deteriorates rapidly. The group is besieged by demons, and in a poignant moment, Rachel momentarily regains control and urges Sarah to run before taking her own life. Tragedy strikes further when Sarah accidentally kills Omar's father in the chaos, leading Omar to take his own life as well, leaving only Kevin and Sarah to navigate the horrors ahead.
Amid their perilous escape, they meet a creature adorned with black wings, unveiling its identity as Sarah's brother, Joel, miraculously returned. He guides them toward safety, but as they traverse the wall's opposite side, Sarah notices she has developed numerous scratches mirroring Rachel's, foreshadowing her tragic fate. Overwhelmed by the transformation, she becomes a demon and ascends into the sky, leaving Kevin in a state of disbelief.
In a haunting final scene, thousands of demons are seen soaring above Jerusalem, with military helicopters patrolling the chaos below as fires rage throughout the city, marking an apocalyptic culmination of their harrowing experiences.
