Saw the latter half of Prime Suspect.
Riveting. Terrific. They know who the real killer is halfway through, and still it's a touch-and-go process. Not to mention there's a whole new twist that makes the prime suspect all the more daunting, and a twist beyond that that stresses Tennison isn't all about revenge, or getting her man no matter what; she does it by the book, she still has faith in the process even if it's frustrating and she sometimes bends the rules a little (between taking an unauthorized trip vs. vigilante action, I guess it's still possible to know where the line is, more or less--what's impressive is that Tennison is able to make that distinction without making too much angsty existential fuss about it). Very impressive bit of TV.