When the new series returns on New Year's Day, the great mystery of how Sherlock survived his 'fatal' fall in the last episode will finally be solved. Keeley Bolger grills the show's stars, Martin Freeman and Benedict Cumberbatch, for clues - but, as ever, they're giving nothing away...
The phrase 'life imitating art' seems very apt for Martin Freeman at the moment. While making the long-awaited third series of Sherlock, the actor found his character, Dr John Watson, in a romantic storyline with Mary Morstan, played by his real life partner of 13 years, Amanda Abbington.
Life for Freeman and Abbington might be less chaotic and puzzling than for Watson and Mary, but the 42-year-old, who made his name as Tim in The Office, is "delighted" to have his partner on board.
"It wasn't a John and Yoko thing, where I said, 'I want my missus in'," says the actor, who has two children with Abbington. "I think they [the casting directors] had thought about it, and I think Amanda is a really good Mary. If she was nothing to do with me, she'd still be someone who'd definitely come up for it."
Delighted though Freeman is about her casting, he's not so thrilled about some people's reaction to the news - Abbington received abusive messages and even death threats on Twitter.
"It's ridiculous. To me, they're not fans of the show - they're fans of a show going on in their heads," he states.
But despite the hate mail, working together's been a positive experience for the couple, who met on the set of Men Only in 2000 and have a "lovely shorthand" when they work together.
"If you're lucky enough to work with your missus or mister, and you actually want to and get on with them, it does help if you're filming away from home," says Freeman, referring to the many car journeys they shared to and from set.
And there are other benefits to having joint jobs, as Freeman adds: "You can see them more than you would normally."
The time together must've seemed all the more precious, given that he'd recently spent the bulk of 18 months away from his family in New Zealand filming The Hobbit trilogy, in which he plays the eponymous lead role.
But as well as a convenient love interest for Watson, much has changed in the world of Sherlock since the last series.
It's set two years after the main character, played by the universally swooned over Benedict Cumberbatch, leapt from a roof and was registered dead after being found in a pool of blood.
The fact that the show's back means the maverick detective's survived and the programme's legions of fans have been busy cultivating theories about how he faked his own death.
Unsurprisingly, Freeman's remaining professionally tight-lipped about storylines.
"You know that ultimately people don't want to hear it," he says. "They'd much rather discover it, and it's just more fun if you see it than if I blow it for you."
In the first episode, Sherlock rises from the grave when he learns that London's under the threat of a huge terrorist attack.
Fans may be counting down the days to watch the first episode, but new director Jeremy Lovering says it won't be the TV screen that he's glued to when the show airs.
"I won't watch the show live," he reveals, laughing. "I'll be on Twitter, seeing whether I am safe to leave my house the next day, or whether there's a group of very angry fans with big sticks outside."
Apart from the threats Abbington received, the show's usually the subject of pleasant attention, with hundreds of fans turning up on set in all weathers to watch filming take place.
"It was peeing it down with rain and everyone was like, 'Oh god, how are we going to get this done?', and the crowd were so encouraging," recalls Lovering of a day on the Baker Street set.
"I remember just looking at them and going, 'They're being so nice', so I went and bought loads of umbrellas to give to them, to repay the support."
Cumberbatch, 37, who worked with Freeman on the new Hobbit movie, is also overwhelmed by the support the fans have shown him and his co-star over the years, not least at a recent screening and Q&A in London where the opening episode of series three was shown.
"I went over the balcony at one point and sort of waved and it caused squeals of delight," says Cumberbatch. "It's a bit weird, to say the least, but I'm thrilled the work has got that big an audience and there's a fascination with this iteration of Sherlock that we've created."
Though his fans would probably find it hard to believe, Cumberbatch admits he felt like an "impostor" when he filmed the second series following a break to work on films.
"Even though it was a longer wait on this series, it felt more comfortable [this time]," he says. "I don't know if that's a good or bad thing. It made me a little nervous - that 'Oh Christ, I got complacent' [feeling], but watching it again, I think even if that is complacency, it's all right.
"There's so much that's familiar, there's so much that I enjoy about him [Sherlock] and want to evolve, and want to change as well," he adds.
If evolution's on Cumberbatch's mind, he's got plenty of time - given that the head of commissioning for BBC drama, Ben Stephenson, recently made a crack about continuing the series for another 50 years.
"I love doing Sherlock. Here's to a few more years at least," says the actor, grinning. "I'm not sure about 50 years, that puts me in my late 80s, but thanks Ben, for that vote of confidence to my health and general wellbeing."
EXTRA TIME - THEORIES ABOUT HOW SHERLOCK FAKED HIS DEATH
:: Rubbish truck theory - The rubbish truck that was parked in front of the building Holmes fell from cushioned his fall.
:: Cyclist theory - The cyclist who knocked Watson over as he dashed to help Holmes was actually one of a network of homeless people he pays to provide him with information. He arranged the whole thing so Watson missed the moment he hit the ground, giving him time to escape and a body double to take his place.
:: Medicine theory - Holmes's brother, Mycroft, plied the detective with fake blood and medicine to give the appearance of death, and paid people to pose as fake surgeons and pronounce him dead.
:: Mask theory - Holmes used his recently-deceased nemesis Moriarty's body to help him fake his fall, covering his face with a latex 'Sherlock' mask before dropping him from the roof.
:: Rubber ball theory - During the last episode of series two, Holmes was seen playing with a rubber ball. Theorists believe he used a sleight of hand trick, whereby squeezing the rubber ball in his palm temporarily stopped his pulse so that he appeared dead.
:: Sherlock starts on BBC One on Wednesday, January 1