In The Middle Ages a village of accused heretics and witches are slaughtered by the The Teutonic Knights. The bodies are buried in a hole and a church is built on top of the burial site to contain the evil spirits.
Fast forward to The '80s when Evan (Tomas Arana), a newly hired librarian uncovers the church's past and unwittingly breaks the seal and releases the vengeful spirits of the slain villagers. The Demonic possesssion or 'contagion' as it is referred to spreads like the common cold and soon, a switch is hit that seals the evil inside. Sadly, a wedding party who show up half way through the movie are trapped inside the Church with demonic spirits.
A few main characters are developed early on, but by the midpoint they're largely forgotten about when the aforementioned wedding party shows up.
- Abusive Parents: Lotte's father, Herman, was abusive to his daughter, sheltering her from what he sees as a Crapsack World.
- Attempted Rape: Possessed!Evan tries to rape Lisa, although he succeeds later on.
- Black Comedy: The grumpy Heinrich and his wife go up to the bell tower, and when the wife sees that there's no rope to pull to ring the bell, she uses his severed head.
- Cold-Blooded Torture: The Architect who designed the Church was tortured by the Teutonic Knights.
- Corrupt Church: A literal example, in that the titular church is corrupted by the evil that resides within it. Although the bishop is a pretty nasty person, too.
- Dark Is Not Evil: Subverted with the bishop, who is often seen wearing a black hood and talking about the Devil. He comes off as grumpy at best, but not necessarily a bad guy. That is, until he reveals his plan to allow the plague to be unleashed upon the city. Ironically, he's wearing a Teutonic Knight garb in that scene.
- Decoy Protagonist: Practically a revolving door of these. Evan, Lisa and Lotte all carry this ball but eventually the movie settles on Father Gus.
- The Dragon: Lotte's Father to Evan after both become possessed.
- Heroic Sacrifice: Father Gus removes the device from the mouth of the Architect which causes the church to collapse
- Humanoid Abomination: Many of the hallucinations, ghosts of people who were killed in the movie, then there's the 'thing' at the end.
- Knight Templar: First off, there's the Teutonic Knights, who were shown to be superstitious and utterly ruthless, killing unarmed villagers who don't do anything to fight back, even burying one of their own men amongst the corpses of the villagers. It's later revealed that they killed the architect that built the Church because they saw him as an alchemist. Second, there's the bishop, who wants the demonic plague to be unleashed upon the city, and presumably the world, which he deems as profane.
- Loads and Loads of Characters: The movie becomes this when the wedding party and shows up.
- Madness Mantra: Evan at his typewriter types "6" over and over.
- Malevolent Architecture: The church was built upon a mass grave of villagers and is inhabited by their
- One-Winged Angel: Some of the possessed take a more demonic form.
- Only Sane Man: Father Gus is one of the only one not possessed (or a Knight Templar) near the end.
- Our Demons Are Different: Different in that they take the form of hallucinations and apparitions, and can assume their true form while inhabiting a human body.
- Religious Horror: Well, for starters, it's set in a (literally and figuratively) Corrupt Church inhabited by demons.
- Sealed Evil in a Can: The ghosts of the villagers are buried far beneath the church.
- Seven Deadly Sins: Some of the ways the characters are enticed to either get into their head or outright kill themselves by the ghosts such as the Bride clawing her skin off her face because she thinks she's an old woman or the biker thinking his girlfriend is making out with a demon.
- The Cameo:
- Black Sabbath star John Richardson cameos as the church's architect in a flashback.
- Director Michele Soavi appears as a cop.
- The Worm That Walks: The ghosts of the slain villagers form an apparition made from a mass of writhing mud-covered naked bodies.
- Would Hurt a Child: Possessed!Evan tries to kill Lotte, who's played by Asia Argento when she was in her early teens.
- You Have Outlived Your Usefulness: After he built the Church, the architect is tortured and left to die with the mechanism to destroy it inside his mouth.