The Friendship Experiment is the return of a show that first came to the Unity in January 2010. After a jaunt to Edinburgh in summer, the rejigged work can now be seen in its spiritual home.

Mini theatre company Big Wow – comprising actors Matt Rutter and Tim Lynskey and director Robert Farquhar – is a labour of love that the trio fits inbetween other major commitments. But their shows are acted out with a real passion for comedy that is addictive.

Stepping on stage in identical jeans, white shirts and blue pumps, Rutter and Lynskey explained that the audience was in for a night of improvised entertainment. Improv, however, turned out to be practically the only thing The Friendship Experiment failed to cram in to its frenetic 75 minutes.

This was a deceptively tightly-written piece. Introducing themselves as Matt and Tim, they proceeded to get into character as friends Steve and Jeff, and spent the rest of the time flitting between being their ‘improv’ characters, their ‘real’ selves, and even breaking out of that to take the piece into a simultaniously touching and mind-boggling meta ending. Jeff took the lead, instructing the seemingly less imaginative Steve. But who’s controlling who, and why..? At its best, even the players seem as if they don’t know.

Almost straight away, you can imagine them on Radio 4, or an Edinburgh Festival staple (and they have worked on both). That style, however, isn’t for everyone and at its worst it can have a cliqueyness to it that can be slightly unappealing, at least at first. But the writing and performances have a charm and a flow to them that are very convincing.

There’s real life anecdotes in the melee, too - they mock a reviewer who once compared them to the Chuckle Brothers, although having seen them, it’s hard to ponder why on earth anyone would say that. As a duo, in they end they were reminiscent of South Park’s Trey Parker and Matt Stone – fast, slick, clever and daft all in one twin pack. The pair are adept at painting a very vivid picture, for example, in one fantastic sketch, using only their physicality to convey a crowded bar of characters.

And like Parker and Stone, there is an enviable chemistry between Rutter and Lynskey which is the glue of the piece and their performances are energetic and all-encompassing. The Friendship Experiment is a complex comedy idea made deceptively simple, even if at one point they breathlessly exclaimed “we’re getting a bit too long in the tooth for all this nobbing about”.

The Friendship Experiment is on at the Unity Theatre until Saturday, January 29.