Now well into its second season, I'm still singing the praises of the Park Theatre, London's newest fringe venue, with its bold artistic direction which offers opportunities to fledgling companies to produce new writing. 8fold theatre's The Door, which was shortlisted for Best New Play Award at this year's Brighton Fringe, is written by joint company director, Cherise Cross. 8fold's aims are to provide thought provoking works and immersive theatre that delves into the machinations of the psyche.  

The Door is based on the author's own battle with insomnia. The protagonist, John (Philip Nightingale) has been a chronic sufferer for two years and reluctantly materialises at a support group for people with related problems, facilitated by Lisa (Adele Keating). Other participants Tim (James Naylor) and Karen (Stephanie Lodge) seem to be overly empathic and eager to assist John in searching for the reasons behind his condition. A mysterious, mostly tacet, Man in Suit (Robert Bradley) hovers in and out without acknowledgement. 

What is never clear from the text, presumably intentionally, is whether or not this is all an enhanced dream-like state that John is experiencing – it's lucid enough to be real.  Were it not for the frequent sounds emanating from within his head – resonant hums, banging of doors, knocking – which, combined with scene shifts in time, cause us a modicum of disorientation, it would be easy to say that he's fighting the natural urges. Lisa's attempt to use hypnosis on John, something that the others claim is "against the rules" only adds to the bewilderment.

Nightingale portrays a man totally on the edge. His frustration and apprehension are palpable and despite an initial laboured dialogue-heavy opening scene with Keating, they soon build up a smooth rapport and the trust flows as she gives a measured sympathetic yang to his yin. In the group sessions, Naylor gives a touching performance as the night-terror sufferer whose sexuality and loss of parental contact has exacerbated his anxiety. 

Despite not really coming to any solid conclusion by the end of the piece, as to what exactly is behind the door that should never be opened, the play did achieve what it set out to – there was much debate afterwards as to what it all meant to each of us. But this isn't necessarily great theatre. There is a distinct lack of satisfaction when tension builds and no resolve appears. Confusing an audience merely creates an abstract connection. Amy Draper's direction isn't at fault though – she moved the pawns in the game adequately and kept the 90 minutes moving apace.

What was excellent, by contrast, was use of space – with audience on four sides we encapsulated the proceedings and all four corners of the Park 90 were utilised – and although the significance of Ele Slade's hexagonal set design wasn't clear, it made for a pleasant distraction to the harshness of the subject matter and Neil McKeown's lighting was beautifully executed. Oscar Wyatt's sound design, however, is awarded top marks – without its atmospheric aesthetic the piece would have little to keep it breathing.

The Door , at Park Theatre

If you're an insomniac, don't think about what's behind a door that you're not supposed to open – you'll never get to sleep! The Door provokes more questions than it answers though the journey isn't by any means uninteresting. At the Park Theatre.