If you want my advice, try not to let anyone tell you what the plot is about. I think it's basic that the viewer must be surprised by the events happening in the film so as to enjoy it as much as possible.
Thus, I won't say anything about the plot except that it contains a bunch of very welcome twists that match perfectly so as to create a well balanced dramatic thriller.
The main character is played by Gustavo Salmerón, who's been a fine actor in the past (specially in "El rey del río" or "Más que amor, frenesí", but who might develop (or so they say)a much more interesting career as a director. I had mixed feelings towards his performance here, but it's probably because I found it hard to discern whether certain characteristics in his diction belonged to the actor or the character. I found the supporting cast more satisfying, specially José Coronado, who is excellent in his dual role.
Technically the film is outstanding, with an excellent use of lighting and music in each of the parts of the story. Newcomer screenwriter/director Vicente Peñarrocha has made a very interesting first work, so it will be interesting to see what he will be bringing in the future.