Who killed Archie? Even EastEnders actors don't know
EastEnders has never played it safe - whether that's by breaking taboos, like giving Mark Fowler HIV when no one else would talk about it, or by allowing a load of teenagers to take over the show as we did with our spin-off series E20 a few months ago - and we're certainly taking a big risk by deciding to do our first ever live episode for our 25th anniversary on Friday, 19 February.
But it's our risk-taking spirit which has brought us our biggest successes and which has made us the greatest British soap of the last 25 years.
I've been executive producer of the show for nearly three and a half years, overseeing all aspects of the show's content and production, and it is an enormous personal privilege for me to steer the show that I've been watching since I was 15 to its quarter century. This anniversary will be a celebration for the audience of all that is great and has been great about EastEnders over the last 25 years.
We'd mapped out a big whodunnit story (Who Killed Archie?), featuring many of our biggest characters and crossing with Ricky and Bianca's (second) wedding, to play leading up to the anniversary night. But we only decided to do a live episode after we worked out the best way to protect the secrets of the story. The cast, the crew and the audience won't learn the identity of the killer until the night. In addition, of course, it's a new and exciting way for the audience to experience EastEnders and a bracing challenge for our cast and crew.
When I first told the cast about it, their responses were very clearly divided between great enthusiasm and deep worry. In the end, if things go wrong (which of course they won't!) the egg will appear to be on their faces. But as time has gone on, they've all become excited by the challenge, and by the opportunity to work in a different way, albeit for one night only.
We'll be rehearsing loads. Run through after run through, drilling our team like an army, building up confidence, ironing out the glitches, perfecting the action.
Simon Ashdown, who has written the script, will be on hand throughout the rehearsal process, working with director Clive Arnold and line producer Sue Mather to get the very best fit between the creative and the practical. It's very complicated.
Usually when a character walks from the interior of the Queen Vic out onto Albert Square, we film it on separate days - the interior in the studio, the exterior on our 'lot'. But for the live we can't do this - to move an actor from one set to the other requires other scenes in between to cover the action. To sort out these issues, there have been a number of people walking briskly around the site holding stopwatches.
I'm so excited about the big night. I'm confident that the performance will go well, and I'm really intrigued to see what the audience make of the outcome. What I'm also really looking forward to is finally not having to live with the worry of knowing who the killer is any longer. There's very few of us who know, and we've had the story mapped out in our heads (not on paper!) for about a year. We live in constant fear of giving it away, talking in our sleep, nodding at the wrong moment.
None of the actors know who did it. We'll be rehearsing a number of scenes in which a variety of outcomes are revealed, but I won't be telling the cast and the crew which one we're doing until the night, moments before we start transmitting.
It's our biggest ever risk, and our biggest ever night, but I wouldn't want it any other way.
UPDATE 17:12 - PS - I'll be writing here on the TV blog again after the live episode - come back on Monday to see how it turned out!
Diederick Santer is executive producer of EastEnders