Those who can't stand improv have concluded it's just a largely empty vessel for show-offs and showboaters. For those stationed in the opposite camp, the art of adlibbing is nothing less than the purest form of comedy with the creative process resulting in one-off moments never to be repeated again. Massachusetts comedian Mike Birbiglia's chamber movie Don't Think Twice might revolve around the fragile existence of a financially struggling but artistically noble improv group called the Communes, but it's ultimately more of a poignant treatise upon friendship, loyalty, ambition and regret.

Led by writer and acting teacher Miles (Birbiglia) who, at the mere age of 36, fears he's close to being washed-up both professionally and romantically, the six-strong troupe (also including Keegan-Michael Key, Gillian Jacobs and Chris Gethard) appears to be a tight bunch. But when producers from Weekend Live (a TV sketch and variety show not so loosely based on Saturday Night Live) attend a Communes gig, the stage is set for internal warfare when Jack (Key) goes against all protocol and grasps the opportunity to sell himself rather than blend with the group. When Jack's career does take a leap forward, it inevitably destabilises the team while providing him with as many problems as he had before fame came calling.

Over the course of 90 minutes, Birbiglia's film packs in as much character detail as he can get away with (from Jacobs' talented but contented Samantha to Tami Sagher's Lindsay is unmotivated yet land-on-her-feet lucky) without sacrificing the human heart that beats away at the film's centre.

As well as keeping you entertained for an hour and a half, Don't Think Twice might well make you look afresh at the likes of Paul Merton's Impro Chums or the Whose Line Is It Anyway? crew and wonder just what is going on behind the scenes once the laughter dies down.

Watch Don't Think Twice at dontthinktwicemovie.com