William Friedkin who directed “The Exorcist” is making headlines.

He just released his new documentary “The Devil and Father Amorth” at the Venice Film Festival and terrified viewers. Now, the official trailer has been released and we see why.

When he made his 1973 classic, “The Exorcist,” Friedkin had never seen an exorcism and for decades he wondered how close he had come to that reality. Last May, he decided to revisit the theme by following “The Dean of Exorcists.” Friedkin sought out Father Amorth after his 1973 film left him with a deep curiosity about the horrifying affliction and the two became quite close.

The non-fiction feature profiles the late Father Gabriele Amortha as he performs his ninth exorcism on an Italian woman, as he fights to expel Satan from her. Friedkin was in the room for the exorcism and it rattled him to the core.

“It was terrifying,” Friedkin told Variety at the Venice Film Festival about recording to the footage. “I went from being afraid of what could happen to feeling a great deal of empathy with this woman’s pain and suffering, which is obvious in the film.”

Rosa, who the exorcism was being performed on had no medical symptoms. It was Father Amorth’s belief that her affliction stemmed from a curse brought against her by her brother’s girlfriend, said to be a witch. The brother and his girlfriend were members of a powerful demonic cult, Father Amorth believed.

SlashFilm has the synopsis of the documentary. The film describes itself as “a startling and surprising story of the religion, the ritual and the real-world victims involved in possession and exorcism”:

“Combining the startling and singular footage from Cristina’s exorcism with interviews from priests and psychologists, neurosurgeons and non-believers, Friedkin guides us on a journey into the twilight world between the boundaries of what we know and what we don’t with a singular and startling guide in the form of the urbane, charming and self-deprecatingly funny Father Amorth, a man who laughs in the face of the Devil both figuratively and literally. Combining Friedkin’s past memories and present observations with archival footage and new interviews – as well as also presenting what may be the only real exorcism ceremony captured on film.”

The film also includes interviews with medical professionals who have examined the possessed woman, as well as conversations with Bishop Robert Barron.

“The Devil and Father Amorth” opens in select theaters on April 20.