The film stars Théo Christine as a twenty-something Banlieue resident who takes home a lethal desert spider that reproduces rapidly and causes a massive infestation in the neighborhood.

One spider ends up in the backroom of a convenience store in Paris, where sneakers dealer and exotic animal lover Kaleb buys it along with a pair of earrings.

Finding Claudia dead, Kaleb and Mathys run back to Jordy, Manon, and Lila, who learn that the spiders belong to the Sicariidae family.

En route to the parking garage, they carefully tread an infested hallway using the time-sensitive hall light to periodically stop the spiders, but fall back in darkness when police gas and shoot at them, during which Jordy gets caught in a web and urges them to leave him behind.

After a struggle with the police, the group is apprehended and taken to the parking garage, where the lieutenant defends the lockdown, which Kaleb dismisses as a failure, as it did more harm than good.

Mathys, after revealing he had been bitten, sacrifices himself by charging through the door leading to the infested hallway, igniting a battle between spiders and armed men.

Later, Manon and Lila tearfully watch the suburb collapse, while Kaleb buries a shoebox containing a childhood photo of him and Jordy in the woods.

On 15 February 2023, Variety reported that principal photography on a French horror film entitled Vermin was underway in Paris, due to be completed on 3 March 2023.

[6] Similarly, Vaniček said he took close-up shots of the spiders with the intention of showing how not frightening but "complex and beautiful" they are, whose aggression in the film stems purely from survival instinct as a result of being taken away from their habitat and being attacked by humans.

[7][9] Thematically, the film highlights social situations in the French suburbs such as class and racial discrimination and police brutality with its depiction of harsh treatment of its characters by both the authorities and the government.

[14] It also reported that the film was attended by 200,000 audiences during its theatrical run and nominated for two César Awards, making it a commercially successful feature directorial debut for Sébastien Vaniček.

[19] According to Screen Rant, the film garnered "overwhelmingly positive reviews for delivering compelling thrills and developing human characters"[3] but polarized audiences over the visuals, which they compared unfavorably with those of 1990's Arachnophobia and 2007's The Mist.

The website's consensus reads: "A chillingly effective creature feature with more on its mind than simple creepy-crawlies, Infested draws viewers into its web with stylish efficiency.

[17] At Slant Magazine, Mark Hanson said the film should satisfy genre fans owing to the precision of the creature effects, but was himself displeased by its conventional narrative as well as sense of urgency to draw tension among audiences at the expense of character development.

[22] Stephen King, the author of The Mist's source novella, published a capsule review on Twitter calling Infested "scary, gross, well made".

[3] Collider ranked Infested 11th in its list of the scariest horror films of 2024, with the writer Daniel Boyer calling it "a chilling breath of fresh air" in its subgenre.