Sherlock producer Sue Vertue has posted an intriguing new photo of Benedict Cumberbatch and Martin Freeman “as they’ll appear in [next year’s] Special”.

Vertue tweeted the above image this afternoon with the hastags “#221back #Sherlock #notkidding”.

The one-off special begins filming in January, with Season 4 shooting later in 2015.

> Here’s everything we know about the special and Season 4 so far.

Earlier today, she posted a photo of the special’s script, commenting: “This is what we’ve been doing today! Later on a pic of Sherlock and John as they’ll appear in the Special #221back”

Writer Mark Gatiss recently hinted: “You can always expect tragedy as well as adventure, that’s just how it goes.”

> Take a look at our Sherlock Christmas gift guide.

What do you think this photo is all about? Let us know below…