Ils

Note the similarities to another well received horror film's poster.

Ils (Them in English) is a 2006 French horror film set in a remote country setting of Romania.

Clémentine (Olivia Bonamy) is a French teacher who has recently moved to Romania with her partner Lucas (Michael Cohen). One night, they hear strange noises and investigate. From there, it gets worse. It turns out that they are being harassed by a group of children, aged from 10 - 15, which might sound like Narm fuel, but turns out to still be as scary as the unknown intruders at the start of the film. Just because they're kids, it doesn't make them any less terrifying.

Ils was well received for maintaining excellent tension throughout (the film only lasts for around 75 minutes, but this is not to its detriment) and for being a scary film without the use of much gore. Most of the scares are of the Nothing Is Scarier variety, with the intruders often just tormenting the couple For the Evulz. The film is also notable for having relatively little dialogue. It's not a feature which has too much attention called to it, but this is a film that people who shy away from subtitled films could manage quite well.

Not to be confused with Them, a 1950s creature feature, They, a thriller from the early 2000s, or the 2008 horror film The Strangers, which has a similar premise.

Tropes used in Ils include:

Absurdly Spacious Sewer: Justified/Averted/Played Straight, whether they are mere sewers (played straight) storm drains (justified, as they need to be larger to allow greater flow of water) or maintenance tunnels underneath a highway (averted, as they are meant to be accessible to people.)
The Bad Guy Wins: Though they avoid Karma Houdini, as they get arrested some time after the events of the film.
Bloodless Carnage: For the film, anyway. Despite being terrifying, the film is almost completely goreless. What is shown is very subtle, and not Squick-inducing at all.
Danger Takes a Backseat: Happens in the prologue.
Downer Ending
Enfant Terrible
Eye Scream: Subverted. A sharp implement is thrust towards Clémentine's eye, but she quickly jerks away just in time.
Foreshadowing: Quite a bit, including the shot of Lucas turning off a TV, which has the hallway reflected in the screen, while the program has a child running past the area the reflection covers. Also, see Fridge Brilliance below.
Fridge Brilliance: For most of the film the Hell Is That Noise sound is not immediately identifiable. But after The Reveal, and the shot showing what makes the sound, specifically a child's toy it becomes apparent that the sound is Foreshadowing The Reveal.
Heel Face Turn: Subverted hard. At first, it seems that one of the attackers turns against the others and tries to lead Clémentine and Lucas to safety. He's faking.
Hope Spot: In the form of a light at the end of a grated-shut tunnel.
Hot Teacher: Clémentine.
Idiot Ball: Averted. The characters don't seem to even own one. They do all the right things, but their tormenters are just very good at being one-step ahead.
It Got Worse: If Clémentine thought getting her car stolen was bad...
Karma Houdini: Subverted.
Kill'Em All: "Five days after the incident, the bodies of Clémentine Savior and Lucas Medvec were found by police..."
Nothing Is Scarier: The intruder's main method of torment.
The Reveal: The killers are children. Young children, who just want to "play."
Very Loosely Based on a True Story: Played straight.