There were many opportunities throughout the movie to make the 'neighbor' more mysterious, more freaky, and more cunning, but these were quickly abandoned in favor of a more clichéd criminal. That is my largest disappointment with this film. Otherwise, it worked well as an action/thriller.
The protagonists are caught up in a mob's smuggling operation, and they use a telescope to spy at people through the window. One day, the girlfriend (Who, I assume by the hero's subsequent panic is never supposed to leave the house) spots something incriminating and is nabbed by the neighbor. (Yes, this is the actual premise of the film, not the more innocent summaries I have read elsewhere. I don't know why they bother hiding the fact that their protagonists are criminals too).
So everybody, who is incidentally criminal, is trying to get one up on each other by sleuthing, tackling, slashing, shooting and your usual hijinks. The movie has good photography, good soundtrack, and is a bit gritty - kind of like the only quality everybody seems to need to survive.