Sherlock season 3 episode 3 will be airing on BBC at 8.30 p.m. on Sunday, January 12, 2014.

In the first episode of season 3 "The Empty Hearse", we saw Sherlock explain to everyone that he was not dead, after the season 2 finale left viewers in suspense when he faked his own death. The second episode "The Sign of Three" saw Sherlock struggling to give the best man's speech at John Watson's wedding to Mary Morstan.

"My first and last vow: Mary and Jon, whatever it takes, whatever happens, I will always be there ... for all three of you," Sherlock said. The episode ends with Sherlock leaving the wedding party and cutting a lonely figure.

The final episode of the new season is titled "His Last Vow" and will see Sherlock Holmes facing nemesis Charles Augustus Magnussen.

The official synopsis is as follows: "A case of stolen letters leads Sherlock Holmes into a long conflict with Charles Augustus Magnussen, the Napoleon of blackmail, and the one man he truly hates. But how do you tackle a foe who knows the personal weakness of every person of importance in the Western world?"

The latest sneak peek preview trailer for "His Last Vow" has been released, which shows Sherlock Holme's enemy set on destroying his life.