READING About this Gives Me the Creeps!

(CNN)A small group of nuns and priests met the woman in the chapel of a house one June evening. Though it was warm outside, a palpable chill settled over the room.

As the priests began to pray, the woman slipped into a trance -- and then snapped to life. She spoke in multiple voices: One was deep, guttural and masculine; another was high-pitched; a third spouted only Latin. When someone secretly sprinkled ordinary water on her, she didn't react. But when holy water was used, she screamed in pain.

"Leave her alone, you f***ing priests," the guttural voice shouted. "Stop, you whores. ... You'll be sorry."

You've probably seen this before: a soul corrupted by Satan, a priest waving a crucifix at a snarling woman. Movies and books have mimicked exorcisms so often, they've become clichés.

The 1973 film "The Exorcist" shaped how many see demonic possession.

But this was an actual exorcism -- and included a character not normally seen in the traditional drive-out-the-devil script.

Dr. Richard Gallagher is an Ivy League-educated, board-certified psychiatrist who teaches at Columbia University and New York Medical College. He was part of the team that tried to help the woman.