On its face, the subject of this documentary -- a contest to determine who can grow the best Donegal beard, an Irish style that doesn't include a mustache -- may not seem gripping enough for film, but it is. Director Mike Woolf manages to mine the drama of the event and tell the history of Shamrock, Tex., at the same time, from its initial incarnation as a once-thriving stop along Route 66 and to its now sleepy, struggling stature.