As somebody who had not heard any of this before, it became a curious phenomenon to sit and watch a film and slowly have the realities begin to click into place.

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.

If you like to be scared, if you like to laugh, and if you like to learn a thing or two at the movies, this absolutely cannot be missed.

After playing with our expectations, this turns out to be a very different sort of film.