I'll tell you why so serious

If the ambition is to provide two hours of instantly forgettable, popcorn-munching escapism, it succeeds.

It's funny, it's tense, it features two great performances from two actors and the director expertly creates a web of odd tension where you actually don't know what is happening for the majority of the run time.

While it doesn't offer any answers, it both thrills and makes you think.