This slick, clever, tightly-choreographed production poses big questions about love and loss, and how we let go when it's time to move on. Yet it's something of a thriller, too. We see figures standing over a hospital bed, where a man named Max is trapped in a world of memories – wrestling with a secret buried deep in his past. A woman has died. Was Max to blame? Nothing here is straightforward, but perhaps by the end we'll find out.

Testament grabs your attention from the very first moments, when two sharply-dressed men stride onto the stage for a pulsating opening homily. One's dressed in white, one's in black, and – as quickly becomes clear – they represent no less than Jesus and the Devil. If you have faith, you could interpret the story as a literal struggle for Max's soul, but to me these men signify something more earthly: the light and shade, self-worth and self-destruction, that exist within his own troubled mind.

That battle takes a physical form, filled with movement and swirling imagery, as Max drifts in and out of consciousness and the truth about his past is gradually revealed. The staging is bold and often exciting, and I'm sure the most striking of the set-pieces will linger long in my mind. But there are quieter, more thoughtful passages too: playwright Sam Edmunds weaves a complex but coherent plot, built around a dilemma in medical ethics but expanding out to contemplate the things we choose to remember, and to forget.

Amidst a six-member cast, Nick Young is superb as Max: at times self-confident and at times deeply frightened, yet defining those emotions subtly enough to seem like two sides of the same coin. William Shackleton plays Max's brother Chris with honesty and heart, channelling the pain of an impossible dilemma and the anguish of seeing a friend tear himself apart. But there is humour too to defuse the tension, as we flash back to glimpses of happier days – and it's satisfying to see Max's mysterious story gradually unrolled, until you know not just the detail of his inner battle, but the series of events that have brought him here.

Somewhere along the way, though, Edmunds' script segues into something I find a little harder to understand. The later scenes seem to be founded on a rather odd belief: that once you face up to grief – once your loss no longer consumes you – then the person you're missing is gone forever, never to be remembered again. Despite his young age, Edmunds is a highly mature writer, and perhaps I've missed a point somewhere amidst his multi-layered imagery. But the allegorical, visceral conclusion left me confused: grief simply don't work this way.

There are a couple of lumpier scenes as well – and the writing makes Max's doctor a little too friendly and accessible, hard to match against the over-worked and professionally-distant figures we all know from our own encounters with healthcare. So Testament isn't perfect, but it's chock-full of thoughtful ideas, and they're all bundled up in a stylish and striking package. It's exciting work from a youthful company… which comes highly recommended to anyone who'll enjoy something gripping, thought-provoking and new.