The romantic triangle form has served film comedy for a long time, and there are some notable ones, such as The Philadelphia Story or, a personal favorite, James Brooks’ Broadcast News. This film, written and directed by Andrew Bujalski, is one in what’s identified as the “mumblecore” genre. While it has pleasures to offer, it’s still (sorry) kind of a letdown.

The chief pleasure is Kevin Corrigan, who just may be the comic genius the NYTimes critic has already dubbed him. He plays Danny, a pudgy, shlubby transplanted New Yorker in Austin who shows up at a local gym to get “in shape”, which means, he explains, being able to “take a punch”. The gym owner is Trevor, a demonically ambitious transplant from Australia played by Guy Pearce. The female part of the triangle, Kat, is the top trainer at the gym, who is assigned Danny as a client. Danny seems to have more money than he knows what to do with, and most of it goes towards things – like pizza, wide-screen TV and weed – that have nothing to do with “getting in shape”. As played by Cobie Smulders, Kat is, at first, even more zealous about physical fitness and getting the best “results” for her clients than Trevor.

But then, she never had a client like Danny. Corrigan pretty much owns the first hour of the film, and each tantalizing revelation of the depth of Danny’s ineptitude makes for some delightful comedy, especially his interplay with Kat, who, quite to her amazement, becomes as attracted to him as he is to her.

I wish I could say the comic fizz kept bubbling but, after a sudden shift in story and tone, what had been a refreshing cocktail becomes a flat Foster’s. Specifically, Bujalski decides to take Danny out of the triangle altogether, devoting the rest of the film to Trevor and Kat. Part of the problem is Pearce, who is simply no megawatt charmer like Redford or Clooney, or his fellow Australian Paul Hogan. Phenomenally muscled, he seems far less strained and pained lifting weights than by having to kiss his co-star. Smulders, on the other hand, is someone to watch. Bringing to mind the young Catherine Keener, in her indie-queen days, she is fresh, game and sexy. Her character’s late conversion is not credible, but that’s probably beyond what any other actress could do.

But the real story here is Kevin Corrigan, and he’s the reason I recommend the film. Danny’s obliviousness is so total, it’s almost sinister. He’s not proud of his faults, but he’s blind to the one that gets him into the most trouble: misunderstanding other people. Corrigan’s line delivery and expression are beyond quirky, falling into downright weird. Think Jack Black crossed with Peter Sellers at his looniest. And Bujalski knows that part of the fun is how uncomfortably the other characters struggle so as not to offend this rich, but impossible misfit.

A final word: this is the most un-Texas Texas film I’ve ever seen. Nobody has a western accent, there’s no horses and the only person who says he has a gun (not shown) is from New York. The characters are positively dripping with SoCal insouciance, and leave puddles. Stupefying!