Maths tests give lots of us nightmares but at least the penalty for failure isn't being crushed to death.
That's the potential fate of the four victims in this ingenious Spanish thriller.
They're brilliant mathematicians invited to an isolated house to solve the greatest enigma ever.
Once inside a locked room they're challenged to solve what seems like a simple puzzle in a minute.
When they fail, they discover that the walls start to move, and the room begins to shrink around them.
The only way out is to solve a series of increasingly fiendish problems.
It's bound to get an American remake but this stylish original is worth the effort.
And it made me wish I'd paid more attention at school.
Fermat's Room is out now.
Karen Dunn
Celebrity Big Brother is back and they're pulling out the big guns Kerry Katona...
Charmian Harris
It's all about skincare on this beautiful Friday...
Alison Tay
Her Majesty Geri Halliwell's anniversary tribute to the monarch
Jess Boulton
Why I stand by my interview with MC Harvey