‘The Lying Detective’ offered a tantalizing lead-in to Series Four’s big finale, the ominously-titled ‘The Final Problem.’ To whet your whistle further, here is the explosive trailer for the episode…
… As well as this short virtual poster, courtesy of the official Sherlock Twitter account.
… And, finally, here’s a bunch of promotional images too. Looking at these, it seems like Mycroft will have a major part to play in this episode. Which makes a lot of sense, considering the major revelations about the Holmes family that will presumably come out in the finale.

WARNING: Embargoed for publication until 00:00:01 on 10/01/2017 – Programme Name: Sherlock – TX: 15/01/2017 – Episode: Sherlock S4 – Ep3 (No. 3) – Picture Shows: **STRICTLY EMBARGOED UNTIL 10TH JANUARY 2017** Sue Vertue, Sherlock Holmes (BENEDICT CUMBERBATCH), Dr John Watson (MARTIN FREEMAN) – (C) Hartswood Films – Photographer: Robert Viglasky

WARNING: Embargoed for publication until 00:00:01 on 10/01/2017 – Programme Name: Sherlock – TX: 15/01/2017 – Episode: Sherlock S4 – Ep3 (No. 3) – Picture Shows: **STRICTLY EMBARGOED UNTIL 10TH JANUARY 2017** Sherlock Holmes (BENEDICT CUMBERBATCH) – (C) Hartswood Films – Photographer: Robert Viglasky

WARNING: Embargoed for publication until 00:00:01 on 10/01/2017 – Programme Name: Sherlock – TX: 15/01/2017 – Episode: Sherlock S4 – Ep3 (No. 3) – Picture Shows: **STRICTLY EMBARGOED UNTIL 10TH JANUARY 2017** Sherlock Holmes (BENEDICT CUMBERBATCH) – (C) Hartswood Films – Photographer: Laurence Cendrowicz

WARNING: Embargoed for publication until 00:00:01 on 10/01/2017 – Programme Name: Sherlock – TX: 15/01/2017 – Episode: Sherlock S4 – Ep3 (No. 3) – Picture Shows: **STRICTLY EMBARGOED UNTIL 10TH JANUARY 2017** Sherlock Holmes (BENEDICT CUMBERBATCH) – (C) Hartswood Films – Photographer: Laurence Cendrowicz
‘The Final Problem’ will be solved on Sunday 15th January, 9PM on BBC One and 7PM on PBS Masterpiece.