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.

The movie turns out to be a little better than the average. Starting from a romantic formula often seen in the cinema, it ends in the most predictable (and somewhat bland) way.

One of the most extraordinary films you will see this year. Take that as you want.