This is a review that tells you how very, very good this production is, without giving anything away. And though I really, really want to tell you whodunit, says Katie Jarvis, I won’t. (Even though you probably already know.)

I’ve been thinking about humankind’s greatest achievements. Walking on the moon; missions to Mars; the internet; inventing writing and the wheel; world peace… Yeah, yeah, blah, blah, blah.

Nope. None of those piffling things. The greatest achievement by far is the fact that around 10 million people have seen the play The Mousetrap and no one has told anyone else whodunit. Astonishing! Puts the wheel to shame. All those people should get a Nobel Peace Prize! Or something.

I left the theatre last night, firmly having to clutch my mouth, desperately wanting to yell to random passers-by, “Guess what! THE MURDERER WAS…”. It’s like being on a tall building and wanting to throw your keys off. Or yodelling at a very quiet moment in church. Let’s face it – we’ve all wanted to do it.

But, just like the yodelling, I managed to stop myself. Just.

On the other hand, if 10 million-plus people have seen it over 60-odd years, that doesn’t leave a huge number on the British Isles who haven’t. So all this mysterious smirking at dinner parties, etc, is probably unnecessary.

Yet still it runs.

The thing about old Agatha is that she goes that extra mile. For one thing, she named her play after the play-within-a-play in Hamlet. And, let’s face it, every good piece of literature owes something to Hamlet, apart from Romeo and Juliet, which was written before. (And that’s a bit iffy in places.) And that’s a clever name, because we all know the Hamlet playlet was staged to catch the conscience of the Kinglet.

And then there are Agatha’s characters and dialogue. She knows how to raise a laugh.

So – the bits I can tell you without jeopardising my peace prize are these. The setting is a country manor, newly inherited by a young couple, whose only way of keeping it is to turn it into a guesthouse. It’s their first night of welcoming guests and, as so often happens when you open a guesthouse, the snow is so bad that the roads are fast becoming impassable, and there’s a murder on the loose. Wouldn’t you just know it!

The guests are trapped; the sinister weather is a pathetic fallacy; and at least most of the characters are concealing secrets from each other.

Are you beginning to smell a rat?

Well, yes, but somehow Agatha makes clichés work. Christopher Wren, the young architect – played so magnificently by Oliver Gully – was so camp that there must be a ‘murder in-tent’ joke in there somewhere. Fabulous fun. Anna Andresen was fantastically I-must-get-on-with-it-despite-these-bothersome-murders Mollie, the guest-house hostess. But, do you know what, I could praise each and every one of the cast for playing their parts so perfectly. I even stopped being annoyed by Mr Paravicini’s foreign accent after a while, which was so odd that I thought, for a bit, it might be a clue. (That’s not a clue, by the way.)

You can quite see why The Mousetrap is so enduring. It was intriguingly entertaining when it was first performed in Nottingham in October 1952; it’s still as much of a jaunt today. This is a great production – it might be a bit cheesy, but don’t be caught out; catch it while you can.

March 21-Saturday, March 26, Agatha Christie’s The Mousetrap at the Everyman Theatre, Cheltenham, Gloucestershire GL50 1HQ, box office 01242 572573; www.everymantheatre.org.uk