It is a true measure of a show’s quality, I think, when it can tell the story of a quirky romp with a multitude of golden one-liners and grin-worthy inside jokes and still manage to keep the sentimental back-beat of the season-long theme going at its core. “Identity Crisis” is, at first glance, a story of a treasure hunt. Through a series of seemingly unconnected events, Mozzie (Willie Garson) discovers a potentially priceless piece of American history and elicits help from Neal (Matt Bomer) and Peter (Tim DeKay) to find it. But it’s more than that, really.