1. A Scandal in Belgravia

Airing 1 January 2012 on BBC1

Written by Steven Moffat. Directed by Paul McGuigan.

Synopsis: In episode one of this new series, compromising photographs and a case of blackmail threaten the very heart of the British establishment but, for Sherlock and John, the game is on in more ways than one as they find themselves battling international terrorism, rogue CIA agents and a secret conspiracy involving the British government. But this case will cast a darker shadow over their lives than they could ever imagine, as the great detective begins a long duel of wits with an antagonist as cold and ruthless and brilliant as himself: to Sherlock Holmes, Irene Adler will always be THE woman.

Loosely based on the novel A Scandal in Bohemia by Sir Arthur Conan Doyle. The opening episode resolves the cliffhanger from the Series 1 finale. It has been described as a “twisted love story.” Lara Pulver guest stars as Irene Adler. In the novel, Adler was one of the few characters to actually outwit Sherlock and earn his admiration.

Returning characters include: Jim Moriarty (Andrew Scott), Mycroft Holmes (Mark Gatiss), D.I. Lestrade (Rupert Graves), Molly Hooper (Louise Brealey) and Mrs. Hudson (Una Stubbs).

2. The Hounds of Baskerville

Airing 8 January 2012 on BBC1

Written by Mark Gatiss. Directed by Paul McGuigan

Synopsis: A Hound from Hell. A terrified young man. Sherlock’s most famous case. But is a monster really stalking Dartmoor? Something terrible has happened to Henry Knight. Sherlock and John investigate the truth about the monstrous creature which apparently killed their client’s father. But what seems like fantasy in Baker Street is a very different prospect in the ultra-secret army base that looms over Dartmoor…

A loose adaptation of Arthur Conan Doyle’s most famous Sherlock novel The Hound of the Baskervilles. The original plot saw Holmes and Watson heading to the moorland to investigate the mystery of a phantom hound. Described as the “Gothic horror” episode with plenty of scares. Russell Tovey guest stars as Henry Knight. Henry recruits Sherlock after “suffering from a traumatic childhood experience”.

3. The Reichenbach Fall

Airing 15 January 2012 on BBC1

Written by Steve Thompson. Directed by Toby Haynes.

Synopsis: James Moriarty – the greatest criminal mind that the world has ever seen. Sherlock and John knew he wouldn’t stay hidden for long. But even they never guessed the sheer scale and audacity of the crime that would propel Moriarty back into the headlines. The crime of the century. The Tower of London, the Bank of England, Pentonville prison – all sprung open on the same day as if by magic! But Moriarty’s plans don’t stop there… Sherlock and John lock horns with their old enemy in one final problem that tests loyalty and courage to their very limits. Sherlock must fight for his reputation, his sanity and his life. But is he all he claims to be?

A loose adaptation of The Final Problem. In the novel, Reichenbach falls was the location where Sherlock Holmes met his end. Holmes fought his arch-nemesis Moriarty above the falls and both supposedly fell to their deaths. Although later revelations proved otherwise.

Returning characters include: Jim Moriarty (Andrew Scott), Mycroft Holmes (Mark Gatiss), D.I. Lestrade (Rupert Graves), Anderson (Jonathan Aris), Sgt Sally Donovan (Vinette Robinson), Molly Hooper (Louise Brealey) and Mrs. Hudson (Una Stubbs).