Finally, after almost three years of waiting (not including The Abominable Bride), Sherlock is returning to our TV screens for season four.

Benedict Cumberbatch, Martin Freeman, Mark Gatiss, Una Stubbs and Amanda Abbington are back as Sherlock, Watson, Mycroft, Mrs Hudson, and Mary, while newcomer Toby Jones will play the mysterious villain Culverton Smith.

So, what time does season four start? Where to watch? And what’s the first episode going to be about? Look no further, as we answer all the key questions below.

What time and where can I watch it?

The first episode of Sherlock season four, titled ‘The Six Thatchers’, will air New Year’s Day at 8.30pm on BBC One.

Sherlock season 4 in pictures Show all 7 1 /7 Sherlock season 4 in pictures Sherlock season 4 in pictures Mark Gatiss and Benedict Cumberbatch in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mycroft Holmes (MARK GATISS) and Sherlock Holmes (BENEDICT CUMBERBATCH) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Una Stubbs as Mrs Hudson in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mrs Hudson (UNA STUBBS) Copyright: Hartswood Films 2016 Sherlock season 4 in pictures Mark Gatiss in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mycroft Holmes (MARK GATISS) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Toby Jones in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Culverton Smith (TOBY JONES) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Martin Freeman in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: John Watson (MARTIN FREEMAN) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Martin Freeman, Amanda Abbington, and Benedict Cumberbatch in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Behind-the-scenes filming 'Sherlock' Season 4. John Watson (MARTIN FREEMAN), Mary Watson (AMANDA ABBINGTON) and Sherlock Holmes (BENEDICT CUMBERBATCH) Copyright: Hartswood Films 2016. Sherlock season 4 in pictures Amanda Abbington, Benedict Cumberbatch, and Martin Freeman in Sherlock Sherlock, Season 4 premieres January 1, 2017 on MASTERPIECE onÂ PBS. Picture shows: Mary Watson (AMANDA ABBINGTON), Sherlock Holmes (BENEDICT CUMBERBATCH) and John Watson (MARTIN FREEMAN) Hartswood Films 2016

What is the episode about?

The episode is loosely based on the Sir Arthur Conan Doyle book The Adventure of the Six Napoleons.

The official synopses reads Sherlock waits to see where Moriarty will make his posthumous move. One mysterious case in particular baffles Scotland Yard - but Sherlock is more interested in a seemingly-trivial detail. Why is someone destroying images of the late Prime Minister Margaret Thatcher? Is there a madman on the loose? Or is there a much darker purpose at work? Something with its roots deep in Mary Watson's past.

Will it be darker than normal?