Steven Moffat teases a looming tragedy in Sherlock season 4

Benedict Cumberbatch is not a guy who rests on his laurels.

The in demand actor recently wrapped principal photography on Marvel's Doctor Strange (which we'll get a trailer for next week), but rather than take a well deserved break he is already back in front of cameras to start filming season 4 of Sherlock.

The start of production was announced by co-showrunner Steven Moffat (via Collider), who dropped some hints on what Holmes and Watson will be up to in the next batch of episodes:

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"Sherlock series four – here we go again! Whatever else we do, wherever we all go, all roads lead back to Baker Street – and it always feels like coming home. Ghosts of the past are rising in the lives of Sherlock Holmes and John Watson bringing adventure, romance and terror in their wake. This is the story we’ve been telling from the beginning. A story about to reach its climax…" Climax...could this be Sherlock's final season?

We also have an official synopsis for the first episode of the new season, which will be directed by Doctor Who veteran Rachel Talalay: "Season 4 begins with the mercurial Sherlock Holmes (Benedict Cumberbatch), back once more on British soil as Doctor Watson (Martin Freeman) and his wife Mary (Amanda Abbington) prepare for their biggest challenge yet: becoming parents."

The Sherlock Christmas special was a bit of a mixed bag for me; while there was typically plenty of fun to be had, having the bulk of the story take place inside Sherlock's mind was problematic. If season 4 is the last we see of this incarnation of Sir Arthur Conan Doyle's characters, here's hoping the show goes out with a bang.

Sherlock season 4 will premiere on BBC 1 in 2017.

Images: BBC