In the age of the
Byzantine Empire, an injured priest wanders through the aftermath of a bloody and desolate battlefield. He comes across an impaled priest in his death throes holding a
Pazuzu head pendant. The priest looks around him and sees hundreds of Byzantine soldiers crucified upside down across the desert. In
Cairo, Egypt in 1949, a young Father
Lankester Merrin struggles with his shattered faith. He is haunted by an incident in a small village in the
occupied Netherlands during
World War II, where he served as parish priest: near the end of the war, sadistic
Nazi SS Lieutenant Kessel, in retaliation for the murder of a German trooper, forced Merrin to participate in arbitrary executions to save a full village from slaughter. Merrin is approached by a collector of antiquities named Semelier who invites him to come to a British excavation in a valley called Derati in the
Turkana region of
British Kenya. The dig excavates a
Christian Byzantine-era
church built circa 500 A.D. — long before Christianity had reached that region of Africa. Semelier asks Merrin to recover an ancient relic of a demon thought to be in the church, before the British can find it. Merrin agrees and travels to the dig site. Father Francis joins him. Upon arriving at the site with their translator and guide Chuma, Merrin meets the chief excavator, a British man named Jefferies with visible
boils on his face, and Sarah Novak, a doctor. In addition, Merrin learns that the diggers are disappearing or leaving in droves because the local tribesmen fear the church is cursed. Merrin witnesses a digger inexplicably experience a seizure. Merrin, Chuma and Francis visit the dig site and find only the
dome uncovered; the rest of the church is buried beneath the earth. Merrin discovers that the church is in perfect condition, as though it had been buried immediately after its construction. The three enter the church through the dome and find the place in near-pristine condition, but note two disturbing oddities; the statues of the angels holding weapons point their spears downward instead of triumphantly toward heaven and someone has vandalized and desecrated the church, placing the cross in an upside-down position. Merrin and Francis deduce that the sculptors were trying to depict the angels restraining something beneath the church. Determined to learn more about the archaeological dig, Merrin asks to consult with the lead archaeologist, Monsieur Bession. Sarah tells Merrin that Bession went insane three weeks earlier and was transferred to a mental hospital in
Nairobi. Merrin visits Bession's tent at the dig site and sees dozens of drawings of the same demon artifact the collector had asked Merrin to find. Merrin visits Bession, but when he enters his room, he discovers Bession has carved a
swastika on his chest and is speaking in the voice of Kessel, who tormented Merrin during the war. Bession then slashes his own throat after saying he is "free". Father Gionetti, warden of the asylum, speculates that Bession was not possessed but rather "touched" by a demon, which drove him mad and eventually to suicide. Merrin is very skeptical, but before he returns to the dig site, Father Gionetti gives him the volume of Roman rituals to use in exorcism, although Merrin claims he will never use them. Upon returning to the village, strange events continue. James, a local boy, is attacked and killed by
hyenas that seem to continuously stalk the dig. His younger brother, Joseph, enters a fugue state after watching James get ripped to pieces. The local chief Sebituana's wife gives birth to a stillborn baby who is covered in
maggots and Jefferies gets attacked in the bar. Around the same time, Merrin discovers a passageway leading to a cave underneath the church that houses an ancient pagan temple with the statue of the demon Pazuzu. He also finds evidence that this temple was used to conduct human sacrifices. Upon his return, he sees the local tribe cremate the stillborn baby. This makes Merrin suspicious because there are stories of an epidemic that wiped out an entire village in the valley 50 years earlier. He had been told that the dead were buried, not cremated, in a graveyard just outside the valley. When he digs up the graves of the supposed victims of this plague, they are empty. Merrin confronts Father Francis about it, and Francis reveals to him the history of the Derati valley. A
great army led by two priests came to the valley searching for the origin of evil 1,500 years prior. When they arrived in the valley, the evil presence consumed them and one killed the other. When the lone surviving priest made it back,
Emperor Justinian ordered a church be built over the site, and then buried to seal the evil force inside of it. The builders of the church never meant it to be recorded in Vatican documents, however, a vague reference to it was recorded and found in 1893. Four priests subsequently came to Derati and enlisted the local tribe to help them. All of the tribesmen and the priests disappeared. The Vatican then ordered that the false graveyard be built and stories of a plague spread around to keep people away from the valley. Francis reveals that it is believed that the valley in Derati was the traditional spot of
Lucifer's fall after the
war in Heaven. Later Merrin, Chuma and Major Granville discover Jefferies tied up in the Church, with his organs pecked out by crows. Merrin discovers that Sarah is Bession's wife and is the possessed individual. She kills Francis before Merrin has the demon exorcised from her in the tunnels below the church, and she dies. Merrin and Joseph emerge from the church, (once again buried in the sand) and
history has repeated itself. Only Father Merrin and Joseph are left as the British soldiers and the local tribes have annihilated each other after blaming each other for the strange occurrences. Sometime later Merrin, once again a priest, returns to
Rome and meets with Semelier at a café, explaining he was unable to find the relic; Semelier replies: "But you found something... didn't you?" ==Cast==