UNDERCOVER...or somesuch

I woke up the other day and while lying in bed, but before actually getting up, I had an idea for a show. I've been racking my brain trying to come up with if it's already been done, and also with the inherent flaw that makes it either unproducible or just unentertaining, but I can't come up with any of those things, so I'm continuing to consider it seriously. Well, that's not entirely true. There is one flaw. That being, it's not a show I would actually watch because it would be way too "dramatic" for my taste. But that doesn't mean that people that watch 24 and Prison Break and Mad Men and things that are completely serious (*cough*self-important*cough*) won't watch it. Anyway, here it is:

An agent (or a small group of agents) from the FBI (or some other significant law enforcement institution) goes (or go, I'm not going to add both tenses from here on; just read plural instead of singular if that's what you're going with) undercover into a suspicious situation for an extended period of time, which allows the agent to become personally involved in...Donnie Brasco...the agent gets to know the people, becomes one of the people, feels conflicted about busting the people. (Seriously, has this been done? Is it happening now? It seems so obvious.) It can work as a series because the agent can go undercover in a new situation in each season (see? like 24), but, if desired, can have regular points of contact outside of the undercover situation that carryover from season to season, like superior officers and family and whatnot. So the mob thing is pretty obvious, but my first idea when I started thinking about it was undercover in a suspected cult. Like one under suspicion for hoarding unlicensed weapons or for child abuse or something. Something that would provide a quirky and varied community for the agent to be involved with. A mole inside Jonestown or the Brand Davidians. How cool would that be? Of course there are tons of other options: aforementioned mob (people want more Sopranos, don't they?); drug trafficking; illegal arms dealing; insider trading; civilian vigilante groups...whatever...anything illegal that involves interaction with a group of people would work.

Anyway, there has got to be a totally obvious reason why that isn't already a show, but one that I'm just not coming up with. Is it too boring? It can't be, considering we're remaking old shows from the 70s and 80s left and right here. I would say it must be whatever the problem was with the unaired (I think) show The Insider(s?), but I was under the impression that was more episodic undercover like 21 Jump Street, rather than extended undercover. Someone please tell me what the problem is. I just wish I could figure out how to make it a quirky dramedy so that I'd watch it. Basically what I want is that episode of Veronica Mars, "Drinking the Kool-Aid", where she goes undercover to investigate a cult under suspicion of extortion, but as a series. Also, it needs a way better name than Undercover. If I thought it would just be about the cult I'd say Drinking the Kool-Aid would be perfect, but obviously that won't work for other situations...unless it would.

In addition, what about an elaborate vengeance scenario? Like Count of Monte Cristo as a series...