In Episode 1 of Season 3, two years after the devastating effects of The Reichenbach Fall, Dr John Watson has got on with his life. New horizons, romance and a comforting domestic future beckon.
But, with London under threat of a huge terrorist attack, Sherlock Holmes is about to rise from the grave with all the theatricality that comes so naturally to him. It's what his best friend wanted more than anything, but for John Watson it might well be a case of "be careful what you wish for"!
If Sherlock thinks everything will be just as he left it though, he's in for a very big surprise...
In Episode 2, Sherlock faces his biggest challenge of all - delivering a Best Man's speech on John's wedding day! But all isn't quite as it seems. Mortal danger stalks the reception - and someone might not make it to the happy couple's first dance.
Sherlock must thank the bridesmaids, solve the case and stop a killer!
In the final episode of this season, written by Steven Moffat, 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?
Benedict Cumberbatch returns as Sherlock Holmes, with Martin Freeman as John Watson, Mark Gatiss as Mycroft, Rupert Graves as Inspector Lestrade, Una Stubbs as Mrs Hudson, Amanda Abbington as Mary Morstan and Louise Brealey as Molly Hooper.
Sherlock is written and created by Steven Moffat and Mark Gatiss, and inspired by the works of Sir Arthur Conan Doyle. Sherlock is produced by Sue Vertue and the executive producers are Beryl Vertue, Mark Gatiss and Steven Moffat for Hartswood Films, Bethan Jones for the BBC and Rebecca Eaton for Masterpiece.