By Michael Ausiello
November 23, 2009 at 03:46 PM EST

Crossover stunts have become as ubiquitous as season-ending character deaths. And let’s face it, more times than not they’re probably conceived at a network marketing retreat instead of inside a writers room — which is probably why many of them come off feeling like blatant ratings-boosting promotional gimmicks. But I’m here to tell you that this week’s NCIS/NCIS: LA mash-up is different, and I can give you at least two reasons why. First off, it revolves around the undeniably awesome Pauley Perrette. And second, because it results in the first face-to-face encounter between Abby and Linda Hunt’s Hetty — a memorable run-in you won’t have to wait ’till tomorrow night to watch thanks to the following exclusive first look…