Perhaps I'm in the minority amongst tonight's audience for Agatha Christie's The Mousetrap in that I've never seen the show. Whilst I was aware that it contained an infamous ending, I had no idea what that plot twist might be – and this review certainly won't spoil anything for those still in the dark.

Famously, this is the longest-running production of any kind in theatre history with more than 25,000 performances over 60 years. But why? What has kept audiences returning to see it over these many years? Quite simply, the story is both pretty ingenious and terrific fun.

The setup is simple. We travel back to 1950s Berkshire to see a group of strangers gather in a country guesthouse only to find themselves snowed in. They soon discover that their party contains a murderer and the story unfolds from there. Each character gets their moment in the spotlight, with grubby secrets and mysterious goings-on revealing themselves in all kinds of unexpected ways.

To say any more about the plot really would spoil the fun but the flashes of high drama are nicely balanced out by numerous farcical moments. Gregory Cox takes the lion's share of the laughs as Mr Paravicini, an unexpected visitor arriving once the heavy snow has really taken hold. Oliver Gully's take on Christopher Wren (no, not that one) is pretty perfect, broadly comedic at first but providing much-needed heart as the story moves forward.

Anna Andresen and Nick Barclay had a nice chemistry as Mr and Mrs Ralston, the lovingly bickering newlyweds who run the guesthouse, while much of the second act is led by Lewis Collier's Sergeant Trotter, a local policeman who arrives on skis to investigate the murder. The cast is completed by Tony Boncza (Major Metcalf), Amy Downham (Miss Casewell) and Sarah Whitlock as the domineering Mrs Boyle.

I really enjoyed being kept guessing as to the murderer's identity and there was much discussion during the interval as to where the story might take us. There were genuine gasps throughout the audience when the final reveal arrived, suggesting that perhaps there were many others who weren't already in the know.

This was a hugely enjoyable production and is well worth seeing during its short run at the New Theatre.

The Mousetrap is a legendary play, and famously secretive. Every audience is asked not to reveal anything to anyone, making them co-conspirators, so that it is even now that holy grail: an Agatha Christie that’s still a surprise. This makes it quite hard to review – I can’t mention the plot, and if I describe the characters I might accidentally give away who’s important either by leaving them out, or by dwelling on them in a double bluff... It could get complicated!

The set is fabulous. It would be worth mentioning even if it weren't the only safe topic. The stage is filled with the great hall of a country house - roaring fire, many doorways with doors that slam satisfyingly, comfy sofas, a stained glass window outside which the snow falls, and falls, until the house is completely cut off from civilisation.

The country manor in question has just opened as a guesthouse, and the cast consists of the young couple who run it and their motley assortment of guests – invited and uninvited – about whom they have done insufficient research. Who has a mysterious past? Who is keeping secrets? Well of course everyone is – this is a classic Christie concoction after all.

While this might sound silly I was unprepared for how entertaining it all was - this is not a grim and serious production. It may be deadly, but it is also funny. The second half is a little static, with a number of serious tête-à-têtes to be had. After all at least one of the characters has some explaining to do!

All in all this is a grand and festive production, worth seeing in its own right and not just for its reputation. Beware - it'll leave you a little spooked but also a little primed with early Christmas spirit. It's all those cosy fireplaces and snow, don't you know.