10 Horror Movies Where The Characters Are All Complete Strangers

Do you know what's even scarier than monsters, killers or apocalypses? Maths!

So many people have spent their school days dreading their numeracy classes, but this Spanish thriller goes above and beyond to show you that the act of mathematics can be far deadlier than you'd expect.

Fermat's Room shows as a group of brilliant mathematicians are brought together and locked inside a room (big shocker there!). The group are then forced to solve maths puzzles, with the walls closing in every time they fail to find an answer before the deadline.

As the plot moves forward, you learn that some of these strangers are more well-acquainted than you were led to believe, making the flick a delicious cocktail of interpersonal drama and intelligence-based tests.

These revelations give the movie some twists and turns that keep you engaged whilst still throwing some high-concept maths your way. Well, maybe it's high concept, but let's be honest, only a few will be able to tell anyway.

The blood-red coloured room also gives the movie some visual flair, and the ensemble acting is strong enough to make every moment convincing. It's not the most violent or shocking movie you'll ever see, but it's as tense as a tightrope walk with no safety net.