Benedict Cumberbatch and Mark Gatiss tease new Sherlock mystery

Benedict Cumberbatch as Sherlock Homes in BBC One's Sherlock - WARNING: Use of this copyright image is subject to the terms of use of BBC Pictures' Digital Picture Service (BBC Pictures) as set out at www.bbcpictures.co.uk. In particular, this image may only be published by a registered User of BBC Pictures for editorial use for the purpose of publicising the relevant BBC programme, personnel or activity during the Publicity Period which ends three review weeks following the date of transmission and provided the BBC and the copyright holder in the caption are credited. For any other purpose whatsoever, including advertising and commercial, prior written approval from the copyright holder will be required.

The creators of BBC One's Sherlock have announced they are creating a new "adventure" called The Game is Now, to be launched later this year.

In a video released yesterday, the hit show's co-creators Steven Moffatt and Mark Gatiss hinted that it would be "not a new episode, and not a new series and not a film... [but] an actual new adventure, a proper one." Online teasers suggest it may be an interactive experience based in London. 

Though no casting for the project has been announced, Moffat promised the adventure will "involv[e] the people you'd expect to be involved in a Sherlock adventure" – and a new video released on YouTube features Benedict Cumberbatch reprising his role as the great detective, alongside Gatiss as his brother Mycroft.

In the video, which takes the form of an "intercepted" audio recording, Mycroft explains that after several operatives have disappeared, his secret network of detectives is "simply short of minds", and will have to recruit some "real people".

"Real people?" says Cumberbatch's Sherlock, incredulous. "Mycroft, you know you can't trust them. They're into all sorts of strange things: high-protein yoghurts, photographs of food, voting..."

There has been much speculation about whether the popular BBC drama – which reached an average audience of 10 million for its fourth series last year – will ever return for a fifth series. Speaking to The Telegraph in March, Martin Freeman (who plays Sherlock's assistant John Watson) said that "people's expectations" had taken the "fun" out of working on Sherlock. 

When asked about Freeman's comments, Cumberbatch told The Telegraph: “It’s pretty pathetic if that’s all it takes to let you not want to take a grip of your reality. What, because of expectations? I don’t know. I don’t necessarily agree with that. There is a level of it [where] I understand what he means. There’s a level of obsession where [the franchise] becomes theirs even though we’re the ones making it."