CBR's 31 Days of Halloween is a daily feature highlighting our staff's favorite horror movies to watch during the month of October. Reader, beware - you're in for a scare!

Polish director Andrzej Żuławski's 1981 horror film Possession creeped out viewers for decades. The dark film features some of the most disturbing images from the '80s, including an underground subway scene that is sure to leave audiences nauseated.

Possession has several major themes and meanings, but it tackles them all in a way where the resulting story is a horrifying masterpiece about falling in and out of love during the Cold War. The film is a cautionary tale about marriage and divorce, but even more so about trust during times of political turmoil. Aside from the film's messages, Possession is a violently haunting monster story guaranteed to scare audiences.

Related: The First Two Hellraiser Films Tell a Perfect Horror Story

What Is 1981's Possession About?

the characters of Possession

Possession is a hazy nightmare-fueled film that turns heartbreak, deceit and relationship anxiety into unimaginable horrors. The film's plot follows Anna (Isabelle Adjani) and her husband Mark (Sam Neill) as their marriage dissolves in West Berlin. Isabelle confronts Mark upon his return from his latest business trip in espionage, declaring she found a new lover and wants a divorce from Mark. He moves out and leaves Anna with their apartment and son Bob (Michael Hogben).

The tumultuous relationship between the two rapidly worsens. Mark discovers that Anna is not taking adequate care of their son and is hardly at home. He meets her new lover, Heinrich (Heinz Bennent), before deciding to hire a private investigator to follow Anna. This is where Possession begins to unveil its hidden nightmare. The private investigator follows Anna to another apartment, this one appearing rundown and largely abandoned. What the investigator discovers in there is startling and horrific. In the apartment is a slimy, inhuman monster. Stunned, the investigator is killed by Anna.

Possession continues down a dark path before the film's staggering finale. After a police chase, Mark ends up hiding in an apartment building, followed by Anna. She shows him the monster, who now looks exactly like Mark. The real Mark and Anna both commit suicide, leaving Mark's uncanny doppelgänger free. He returns to Anna and Bob's apartment, where inexplicably waiting for them is Helen (Anna's own doppelgänger and Bob's teacher). Possession ends with this couple reuniting.

Related: Halloween Ends Quietly Confirms a Popular Theory About Michael Meyers

Why Possession Is Mandatory Halloween Viewing

Movies Possession Isabelle Tunnel Scene

Possession is a must-watch this Halloween for a few different reasons. The film explores the darker depths of marital problems, drawing from Żuławski's own experiences with divorce. Relationships are built on certain levels of trust, but it's close to impossible to trust someone completely. Feelings change, people grow up and apart, and the world is constantly evolving. Possession materializes these fears and places them in this strange, inhuman monster that Anna is infatuated with. The title of the film also hints at these themes of relationships and the misery they can bring; Anna is never truly "possessed" by an outside force, but her feelings of love, hurt and betrayal possess her and lead her down a dark path of violence and madness.

Adjani's portrayal of a tortured Anna has landed Possession its place within feminine horror. Combined with its themes of anxiety and a decaying marriage and its sociohistorical context, Possession is a cautionary tale about love and the extent that people can know their partner. Possession's setting in West Berlin during the Cold War only heightens these anxieties, as a split Berlin represents the decay of trust between people and nations. The Berlin Wall looms in the background of Possession, marking the separation between West and East and showing that even though the distance between the two is small, there are larger forces in play to keep them apart.

The theme of the doppelgänger is noteworthy in Possession as well. While this is a relatively common trope in horror, Possession's use of the double ties back in with its themes of relationships and the decay of love. Mark's doppelgänger is born out of a monster, nurtured and protected fiercely by Anna before it even takes the shape of a human. Anna is looking for someone who will stay with her always, unlike Mark, who is often absent from the household. Possession takes horror tropes like otherworldly monsters, blood and violence and the doppelgänger to heighten its themes and cement its darkness.

Related: Saw - Halloween Horror Picks

How to Watch Possession - Is the '80s Horror Film Streaming?

Anna in Possession

Unfortunately, Possession is unavailable to watch on streaming services in America. The cult horror film is not even available for rent or purchase on iTunes or Amazon Prime Video, leaving physical DVDs the only way to watch the film. Interestingly enough, the film was not meant to be some hidden, underground film. Possession is a European art-house film that premiered at the Cannes Film Festival, even securing Isabelle Adjani a win for Best Actress. Possession has increased in popularity over the years, holding its spot as a cult horror film. Maybe the 1981 horror film will make its way to a streaming service soon!

Related: 4 Underrated Dark Comedy Movies to Watch This Halloween That Aren’t Hocus Pocus

Possession is one of the most jarring horror films of the 1980s, and its cult status has kept it out of the mainstream for quite a while. Although it's not currently available to stream, Possession and its twisted love story make it the perfect film to add to one's watchlist. Fans of monsters, evil personas and messy marriages may find the perfect film in 1981's Possession.