BBC One has released a new picture for the upcoming special episode of Sherlock.

The episode, which will not be connected to the usual series, sees Benedict Cumberbatch and Martin Freeman reprise their roles as Sherlock Holmes and John Watson, but instead of the modern version we’re used to seeing, the crime-fighting duo will play the Victorian version of their characters in 1895. Details of the how and why? are being kept under wraps.

There is no official airdate for the special, but it’s likely to be over the Christmas/New Year period. A further three episodes of the BBC One series will commence filming in 2016.