I consider Pod Prikritie, Season 1, to be as good as anything ever produced for TV anywhere in the world.
The show's original writing team (T. Vasileva and G. Ivanov) impress in Season 1 with creating fascinating characters, setting up the major conflicts and intricate story lines within the Bulgarian Mafia underworld.
The story, as the title ("Undercover") suggests, is about a cop who infiltrates an underworld organization. Yes, it's been done before, most recently in "The Departed", which was itself a Hollywood remake of a Hong Kong movie. The twist here is, well, it's a social commentary disguised as a TV series about the Bulgarian mafia.
The actors are all top notch. One actor's performance in particular stands out as a tour-de-force. Not enough can be said about the brilliant Mihail Bilalov, as the sociopath/crime boss "Jaro" (Peter Todjarov), who dominates throughout Season 1. It would be an understatement to say that he steals every scene.
Bilalov's Jaro is that rare performance that reminds one of the power of Anthony Hopkins' Hannibal Lecter in "The Silence of the Lambs". In fact, if Hannibal Lecter was a Bulgarian crime boss, he might have been somebody much like Jaro. Only, he would be cannibalizing an entire society.
(As an interesting bit of trivia, Mihail Bilalov only recently resurrected his acting career. Previously, he had given up acting for the past 20 years and worked as a landscape architect in France.)
The directors of the series have done a great job of getting the story on film with impressive visual flare. There is plenty of heart-pounding action, poignant drama, sex, forbidden romance, black comedy and nerve-rattling suspense.
The series, which is filmed in Bulgaria, has the production values one usually sees only in major Hollywood studio productions. At the moment (January 2013), Pod Prikritie (Undercover) is only available on Bulgarian TV or on the internet (without English subtitles).
Pod Prikritie has universal qualities and it will definitely appeal to international audiences. The series has been bought by an American company (New Films International) and, hopefully, will eventually be distributed in other markets.
I would not be surprised if this show ends up getting remade by Hollywood one day.
Season 1 is brilliant. (I attribute this fact most of all to the original writing team. Watch the pilot of the series for a master-class demonstration of how to set up a gripping story and introduce unforgettable characters.)
Season 2 is... well, still very good. (Although, one can see that the series has lost the brilliance of Season 1. Hint, the original writers - Vasileva & Ivanov - moved on to work on a different show and were replaced by other screenwriters.)
Season 3 is... unfortunately, a rather mediocre type of affair. Gone is the sophistication of the story lines and characters. Even the great Bilalov does not have much to work with here. The writing gets better around mid-season, but it's obvious that the whole production has failed to sustain the high standards of Season 1 and Season 2... The story lines and the characters are much more "on the nose" and uninspired. (Hint, again, the writing team of Season 2 were replaced by new writers and you can tell.) In Season 3 there is more emphasis on pure action and less on character development and suspense. It actually feels like a different series altogether.
Overall, this is a series worthy of a worldwide audience. My advice is to watch Season 1 & 2 (the story wraps up nicely with Season 2). But beware of potential disappointment with Season 3 and proceed at your own risk.