Exorcist II: The Heretic is a 1977 American supernatural science fiction horror film directed by John Boorman and written by William Goodhart. It is the second installment in The Exorcist film series and the sequel to The Exorcist (1973), and stars Linda Blair, Richard Burton, Louise Fletcher, Max von Sydow, Kitty Winn, Paul Henreid, and James Earl Jones. It was the last film to feature veteran actor Paul Henreid before his death on March 29, 1992. Set four years after the previous film, the film centers on the now 16-year-old Regan MacNeil, who is still recovering from her previous demonic possession.

Exorcist II: The Heretic was theatrically released in the United States on June 17, 1977, by Warner Bros. The film received generally negative reviews from critics and is often considered to be one of the worst films ever made. Despite earning over $30 million domestically against a $14 million production budget, the negative reception meant that the next film in The Exorcist series would not come until The Exorcist III on August 17, 1990.

Plot Philip Lamont, a priest struggling with his faith, attempts to exorcise a possessed woman in Latin America who claims to "heal the sick". However, the exorcism goes wrong and the woman knocks over lit candles, setting the place ablaze, and a candle inadvertently sets fire to her dress as well, killing her. Afterward, Lamont is assigned by the Cardinal to investigate the death of Father Lankester Merrin, who had been killed four years earlier in the course of exorcising the Assyrian demon Pazuzu from Regan MacNeil. The Cardinal informs Lamont that Merrin is facing posthumous heresy charges because of his controversial writings, as Church authorities are trying to modernise and do not want to acknowledge that Satan exists.

Regan, although now seemingly normal and staying with her guardian Sharon Spencer in New York City, continues to be monitored at a psychiatric institute by Dr. Gene Tuskin. Regan claims that she remembers nothing about her ordeal in Washington, D.C., but Tuskin believes that her memories are repressed.

Father Lamont visits the institute, but his attempts to question Regan about the circumstances of Merrin's death are rebuffed by Tuskin, who believes that Lamont's approach would do Regan more harm than good. In an attempt to plumb her memories of the exorcism, and specifically the circumstances in which Merrin died, Tuskin hypnotizes Regan, to whom she is linked by a "synchronizer", a revolutionary biofeedback device used by two people to synchronize their brainwaves. After a guided tour by Sharon of the Georgetown house where the exorcism took place, Lamont returns to be coupled with Regan by the synchronizer. The priest is spirited to the past by Pazuzu to observe Merrin exorcising a young boy, Kokumo, in Africa. Learning that the boy developed special powers to fight Pazuzu, who appears as a swarm of locusts, Lamont journeys to Africa, defying his superior, to seek help from the adult Kokumo.

Kokumo has become a scientist studying how to prevent locust swarms. Lamont learns that Pazuzu attacks people who have psychic healing abilities. Regan is able to reach telepathically inside the minds of others; she uses this to help an autistic girl to speak as she waits to see Tuskin. Tuskin and her staff are shocked, but the girl's mother is too overjoyed to care, and despite Tuskin's attempt to keep them in the office to figure out what happened, insists on going home so the girl's father can hear her as well. Father Merrin, who belonged to a group of theologians that believed psychic powers were a spiritual gift that would one day be shared by all people, thought people like Kokumo and Regan were forerunners of this new type of humanity. In a vision, Merrin asks Lamont to watch over Regan.

Lamont and Regan return to the old house in Georgetown. The pair is followed in a taxi by Tuskin and Sharon, who are concerned about Regan's safety. En route, Pazuzu tempts Lamont by offering him unlimited power, appearing as a succubus who is a doppelgänger of Regan. The taxi crashes into the Georgetown house, killing the driver, but Tuskin and Sharon survive; at the front of the house Sharon sets herself on fire. Although Lamont initially succumbs to the succubus, he is brought back by Regan and attacks her doppelgänger while a swarm of locusts deluges the house, which begins to crumble around them. However, Lamont manages to kill the doppelgänger by beating open its chest and pulling out its heart. In the end, Regan banishes the locusts (and Pazuzu) by enacting the same bullroarer ritual attempted by Kokumo to get rid of locusts in Africa (although he failed and was possessed). Outside the house, Sharon dies from her injuries and Tuskin tells Lamont to watch over Regan. Regan and Lamont leave while Tuskin stays to answer police questions.

Cast Linda Blair as Regan MacNeil Kitty Winn as Sharon Spencer Richard Burton as Father Philip Lamont Louise Fletcher as Dr. Gene Tuskin Max von Sydow as Father Lankester Merrin Paul Henreid as Cardinal Jaros James Earl Jones as Kokumo Joey Green as Young Kokumo Ned Beatty as Edwards Rose Portillo as Spanish Girl Barbara Cason as Mrs. Phalor Richard Paul as Plane Passenger Ken Renard as Abbot Hank Garrett as Conductor Dana Plato as Sandra Phalor (uncredited) Karen Knapp as Pazuzu (uncredited voice)

Production Development Neither William Peter Blatty nor William Friedkin, the writer/producer and the director, respectively, of the original The Exorcist, had any desire to involve themselves in an Exorcist sequel. This was because they had filed lawsuits against both the studio and each other over profits, credits, and Blatty being barred from post-production during the first film. According to the film's co-producer Richard Lederer, Exorcist II was conceived as a relatively low-budget affair: "What we essentially wanted to do with the sequel was to redo the first movie... Have the central figure, an investigative priest, interview everyone involved with the exorcism, then fade out to unused footage, unused angles from the first film. A low-budget rehash — about $3 million — of The Exorcist, a rather cynical approach to movie-making, I'll admit. But that was the start".

Playwright William Goodhart was commissioned to write the screenplay, titled The Heretic; he based it around the theories of Pierre Teilhard de Chardin (the Jesuit paleontologist/archaeologist who had inspired the character of Father Merrin in Blatty's novel The Exorcist). Goodhart's screenplay took a more metaphysical and intellectual approach compared with the original film. Here, the battle between good and evil would center on human consciousness—with the specific idea that, within the framework of Catholic theology, human consciousnesses could be brought together as one through technology, although this would also result in conflict between those who sought good and evil.

Sam O'Steen initially agreed to direct the film, but never officially attached himself to the production. British filmmaker John Boorman signed on to direct, stating that "the idea of making a metaphysical thriller greatly appealed to my psyche". Years earlier, Boorman had been considered by Warner Bros. as a possible director for the original film, but he turned the opportunity down as he found the story "rather repulsive". However, he was intrigued with the idea of directing a sequel, explaining that "every film has to struggle to find a connection with its audience. Here I saw the chance to make an extremely ambitious film without having to spend the time developing this connection. I could make assumptions and then take the audience on a very adventurous cinematic journey".

Casting Linda Blair agreed to reprise her role of Regan MacNeil for Exorcist II, but refused to wear demon make-up (a double was used for the brief flashback scenes depicting a demonic Regan). Max von Sydow was persuaded by Boorman to reprise the role of Father Merrin; he was initially reluctant to return because of his concerns over the negative impact of the first Exorcist film. Kitty Winn signed on to reprise the role of Sharon Spencer for Exorcist II after Ellen Burstyn flatly refused to return as Chris MacNeil.

Boorman contacted William O'Malley to reprise his role as Father Joseph Dyer from the first film. However, O'Malley was busy and could not take up the part, and the character of Father Dyer was changed to Father Philip Lamont. Jon Voight, David Carradine, Jack Nicholson and Christopher Walken all were considered for or offered the part of Father Lamont, who John Boorman initially conceived as a younger priest in awe of Father Merrin's writings. As mentioned in Variety, Voight initially signed on for the role but left in April 1976 when "differences about the role could not be resolved". He was replaced with Richard Burton signing on for the role.

The role of Dr. Gene Tuskin was originally written for a man, with Chris Sarandon and George Segal both considered. When the sex of the character was changed, both Ann-Margret and Jane Fonda were under consideration. Louise Fletcher, who had just won the Academy Award for Best Actress for One Flew Over the Cuckoo's Nest (1975), accepted the part.

Screenplay and filming Principal photography began at Burbank Studios on May 24, 1976, with a budget of $11 million (the film ultimately cost $14 million to make). Although Boorman wanted to film the majority of the film on location (including Ethiopia and The Vatican), many of his plans proved to be impossible, resulting in key exterior scenes having to be filmed at the Warner Bros. backlot. Even the MacNeil house in Georgetown had to be replicated in the studio because the filmmakers were refused permission to film at the original house. The filmmakers also had to replicate the infamous "Hitchcock Steps" adjacent to the MacNeil house, as they were refused permission by Washington city officials to shoot scenes by the real steps.Bob McCabe, The Exorcist: Out of the Shadows (Omnibus Press, 1999), pp. 160–162 There were also two weeks of filming in the New York metropolitan area. A key scene of a sleepwalking Regan about to wander off a rooftop was filmed in New York City, atop 666 Fifth Avenue (where the studio's offices were then located). With no stunt person and no special effects, the shot showed actress Linda Blair's feet on the edge of the building with Fifth Avenue down below.Pallenberg, Barbara. The Making of Exorcist II: The Heretic. New York City, Warner Books, 1977. Scenes were also filmed at Pennsylvania Station in Newark, New Jersey.

Boorman was unhappy with Goodhart's script and asked Goodhart to do a rewrite incorporating ideas from Rospo Pallenberg. Goodhart refused, so the script was subsequently rewritten by Pallenberg and Boorman. Goodhart's script was being constantly rewritten as the film was shooting, with the filmmakers uncertain as to how the story should end. Linda Blair recalled: "It was a really good script at first. Then after everybody signed on they rewrote it five times and it ended up nothing like the same movie".

Exorcist II was beset by numerous problems during production. Boorman contracted a case of San Joaquin Valley fever (a respiratory fungal infection), which canceled production for over a month (a costly delay). Other problems included footage being oversaturated and necessitating reshoots; the rapid deaths of locusts imported from England for the film's climactic scenes (2500 locusts were shipped in and died at a rate of 100 a day); original film editor John Merritt quitting the production (he was replaced by Tom Priestley), and stars Kitty Winn and Louise Fletcher both suffering from gallbladder infections.Bob McCabe, The Exorcist: Out of the Shadows (Omnibus Press, 1999), pp. 160–163