Gerard Reve, an alcoholic, bisexual novelist, travels from Amsterdam to Vlissingen to give a lecture to the city's literary society.

During the lecture, Gerard notices the society's treasurer, a cosmetologist named Christine Halsslag, incessantly filming him with a handheld camera.

Later, in Christine's salon, Gerard finds a photograph of her attractive German lover, Herman, and realises he is the same man he encountered at the train station.

Gerard swiftly becomes enamored with Herman, and agrees to have an extended vacation with Christine in hopes of encountering and ultimately bedding him.

Gerard halts the encounter with Herman and confesses his belief that Christine is responsible for her three husband's deaths, and that either of them could fall victim to her.

When the two men depart the cemetery, Herman loses control of the car near a construction site and collides with a bundle of iron rods being lifted by a crane, which impale him through his eye socket, killing him.

A traumatised Gerard is taken to a hospital for examination, where he tells the physician, Dr. de Vries—an acquaintance of Christine's from the literary society—that she is a witch who leads men to their deaths.

Ideally, it would be nice to believe that there is a God somewhere out there, but it looks to me as if the whole Christian religion is a major symptom of schizophrenia in half the world's population: civilizations scrambling to rationalize their chaotic existence.

"[3] Reve endures many experiences which may be hallucinations, such as a famous scene in which he believes a woman is pointing a gun at him, then turns to show it is merely a key to a door, and another in which, on a train, he studies a picture on the wall so intently that he is apparently drawn into it.

Mike Pinsky of the website DVD Verdict points out repeated motifs, including the red, blood, as well as the religious images of the Virgin Mary, and the Cross, including: images of a spider climbing over a crucified figure of Jesus pursuing a fly; Reve's character tipping his glass to a statue of the Virgin Mary; a woman peeling an apple, and holding the peel in the shape of a halo over her son's head; and a sign that reads "Donate Your Blood to the Red Cross".

"[5] Film scholar Charles Derry notes in his book Dark Dreams 2.0: A Psychological History of the Modern Horror Film from the 1950s to the 21st Century (2009), that "what makes The Fourth Man especially interesting—despite its misogyny (typical for horror) that turns women into symbols, updating the archetypes of the whore and virgin into the super-archetypes of the she-devil and Virgin Mary—is that the homosexuality of the protagonist is presented as a positive moral alternative to the heterosexuality of the femme fatale.

[8] The Seattle Times, in a rave review, wrote that the film is "confident and skillfully made" and "erotically charged (and graphic)," adding, Verhoeven has created an intricate, witty thriller about a writer's fears and paranoid imaginings and their possible fulfillment ...

Usually movies that take this approach (like Jack Clayton's delicately balanced masterpiece of ambiguity, The Innocents) are too frustrating to American audience expectations to become commercially successful.

Verhoeven makes the writer's suspicions so entertaining that his dreams and fantasies, which might just be premonitions, have a visual and psychological force that is actually stronger than the 'reality' of the other characters.

Verhoeven gives us plenty of hints that we should not take things too seriously, particularly through Gerard's erratic behavior: his childish lust for Herman, his desperately facile attempt to fake psychic powers in order to trick Christine, and his increasingly baroque hallucinations.

After writing this, Pinsky adds, "Verhoeven is quite clear up front that the movie is meant to be a joke and that Christine's guilt is deliberately ambiguous ...