Good story, Not enough for a whole film

I cannot think of one single thing that I would change about this film. The acting is incomparable, the directing deft, and the writing poignantly brilliant.

The film never slows down or bores, plunging from one harrowing sequence to the next.

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.