By BARBARA THOMAS
Cox News Service

"The exorcist," that terrifying best seller about a child possessed by a devil, has been converted into the singularly most horrifying film ever made. It is even more horrifying to learn the film was based on an alleged documented event.

Lines of anxious patrons watched shattered viewers leaving the theater on opening night. One woman rushed for the ladies lounge, nauseated from fear, and most who left the showing were ashen-faced from the experience.

William Peter Blatty, author of the original work, wrote the screenplay and produced the effort, resulting in a film even more chilling and realistic than the book that caused many a sleepless night for millions of readers.

The film is almost indescribably terrifying and director William Friedkin, responsible for the success of "The French Connection," deserves most of the credit.

Jason Miller, playwright who penned that super hit "That Championship Season," makes his film debut as Father Karras, the doubting, guilt-ridden priest who assists in the exorcism. He has proved to be almost as good an actor as a writer, but it is difficult to concentrate on the finer points of the film for being caught up in its terror.

Some will find parts of the exorcism and the child's exhibition of the spirit too hideous to take. But Blatty's intent is to terrify and that he does.

For those not familiar with the book, it is the story of a famous actress who discovers her child behaving most peculiarly. After extensive medical examinations and visits to the psychiatrist, the mother decides the child is possessed. The child begins talking in strange voices, shrieking and committing obscenities and violently abusing herself and any who approach her. A young priest psychiatrist, obsessed with guilt over his recently dead mother, is called in to perform an exorcism.

Any who plan to see the film should plan on a long wait. One young girl at the front of the opening night line who had apparently been waiting for some time fainted, either from heat, exhaustion or excitement.

The film is based on a reported exorcism of a 14-year-old boy in Mt. Rainer, Md. Blatty became interested in the subject while he was attending Washington's Georgetown University, where the film is set.

The actual case upon which Blatty based his novel, which has sold more than six million copies, was reported in the Washington Post in 1949, as well as in the Daily News and Times Herald.

Blatty's novel is chillingly similar to the events reported in the 1949 incident. During the exorcism, performed by Jesuit priests, brandings spelling out the word "Hell," appeared on the boy's body, some of them drawing blood. After extended periods of violent seizures, profanities and other abuses, the boy was finally exorcised, and in the midst of the most violent spasms, during the incident he uttered, "He is gone."

Anyone who has not already read the book should think twice before seeing the film. It is impossible to imagine the terror unless forewarned.