Not sure it's available on instant, but this mini-series was a really, really gripping to watch...
The Staircase
It's a documentary about a real life trial (from about 2003 in NC), so if you're familiar with the story the spoilers may undermine the way the drama unfolds. And the filmmaker may have had a bit of a selective eye.
Still really gripping. Mrs Q and I watched the first 2 or 3 segments on a normal schedule, and then force-marched through the last 5-6 hours in one white knuckle all-nighter.