The Door, Park Theatre, review The physics ambitions of The Door are obvious from the very first line. Our protagonist, John (Philip Nightingale), stands beneath hexagonal, atom-like structures, while a voiceover talks of quantum entanglement. The phenomenon is explained by the idea of two cups, which, once met, will always be affected by the other, no matter the distance between them. Unfortunately, the cup analogy is about as sophisticated as it gets. Vague questions of alternate worlds (or perhaps just alternate mindsets) muddle through this play about a man with insomnia who seeks help in group therapy. The cheesy group sessions would be grist to the mill for any therapy-sceptic, though the games and discussions make for engaging plot development. The other two group patients are intentionally (I hope) irritating as they delve into their personal angst, and John mixes annoyance with sporadic bursts of anger as he struggles to open up. John claims that he's just a normal guy who lives a life of computer games and work spreadsheets, and feels bad that there's no tragic cause behind his ailment. His trouble sleeping is presented as a mystery, though in the end, it turns out John is suffering from a good old-fashioned existential crisis. In his big breakthrough, he talks of feeling "trapped, living the same day every day" and complains of a "void filled with emptiness." It's Camus 101, but it's a shame it took most of the play to reach such a predictable psychological concern. The main relationship in the play is between John and his patronising therapist, Lisa (Adele Keating), who is confidante of choice despite her dubious therapy techniques. There's absolutely no sexual tension between the two, which makes any scripted references to their emotions ("You didn't think I was asking about your girlfriend because I'm interested, did you?") seem more funny than meaningful. And Keating doesn't always come across as the likeable character she's supposed to be. But the biggest problem, which turns the play from flawed but watchable to confused and messy, is the half-baked psychological thriller aspect. Throughout the play, the sound of a door banging shut haunts John, representing his psychological anxiety. And a mysterious character who seems to represent John's subconscious shows up at moments of self-scrutiny. But the final ten minutes introduce some rushed suggestions about what lies behind the door, the truth behind this subconscious figure, and the implications for John's current "half-lived life." In all, they don't add up to a meaningful theory. Either playwright Cherise Cross hasn't included enough detail to truly showcase her ideas, or she hasn't quite figured them out herself. Until December 1. Tickets: 020 7870 6876; parktheatre.co.uk