Sherlock Holmes and Dr Watson have solved 'The Final Problem' - but was that really the last we'll see of the Baker Street Boys?
There have been conflicting reports as to whether or not Sherlock is over for good, with plenty of chatter to suggest that the great detective could perhaps stage another resurrection.
Sherlock season 5: Is it going to happen?
Is there life in the great detective yet? Series co-writer Steven Moffat stated in mid-2016 that "it's unlikely" Sherlock will disappear entirely - comments echoed by his cohort Mark Gatiss in 2015.
"We're all constantly thrilled and amazed by people's enthusiasm for Sherlock," he told Digital Spy at the time. "We hope to carry on as long as we can."
"Re: Sherlock's future - for those of you asking, it's definitely the end. Of Chapter One," Moffat later wrote in January 2017, after the fourth series had aired.
"Dr Watson is now Doyle's brave widower and Sherlock Holmes has become the wise and humane version of the main run of the stories (we've focused, so far, on the cold Holmes of the early days.)
"Whether we ever get to Chapter Two - our boys consciously living the myth and battling wrong-doers - rather depends on our two stars. I'd be slightly surprised if we never made it again. But I've been surprised before."
By June, Moffat was still operating under the assumption that Sherlock would return at some point. "I sort of assume we will. I sort of assume we'll come back.
"We did [the last series] a year ago, just about, and I've been flat-out on Doctor Who ever since. So I haven't really thought about it. Mark been doing other stuff as well, so we haven't sat down and had a proper talk about what we would do with another series."
While it's possible he'll simply be too busy to continue - more on that later - Benedict Cumberbatch has spoken of his desire to play Sherlock well into old age - Sussex farm, beekeeping and all.
"The idea of never playing him again is really galling," he said, while cautioning that "it's not going to happen again at the same regularity that it has been happening."
One thing's for certain - Sherlock without Cumberbatch (or Martin Freeman) is NOT an option: "We couldn't do it without him, of course not," Gatiss insisted. "We couldn't recast Sherlock"
Sherlock season 5 air-date: When could it premiere?
Sherlock's scheduling has been anything but regular: with an 18-month gap between its first two series, a wait of two more years between series two and three, a one-off special after another two-year wait, then one more series of three films after another 12-month break.
So given that we've been warned to expect a long wait, how long could we realistically be looking at before we (potentially) get more?
On the decision to kill off Mary (Amanda Abbington) in series four's opener rather than its finale, Moffat explained that he didn't want to have to wait "two years" to explore the resulting rift between John and Sherlock.
So could we get another series - or at least a special - in 2019? It's not out of the question, but Moff may just have been speaking very generally... and 24 months isn't much longer than we've been made to wait in the past.
Speaking on The One Show in June, Andrew Scott - Jim Moriarty - said: "I don't think there's another series of Sherlock coming soon. We're not doing it for another couple of years. Everybody got quite busy, you know? [And] you want to keep it fresh."
Gatiss later suggested that the wait would be "even longer" than two years. "We have no immediate plans [to continue]," he added.
Sherlock season 5 cast: What's holding up more episodes?
From the mouth of Moffat: "The ratings were extremely good so I guess they'll ask us [to do Sherlock] again, and then we'll have to see first of all if we have three films we want to make, and then if Benedict [Cumberbatch] and Martin [Freeman] have the time, schedule and inclination."
Yes, the big thing stalling more Sherlock is that the cast are booked up on other projects, especially the show's two leads.
Cumberbatch is now tied to a multi-picture movie deal with Marvel - plus he's an Oscar nominee these days, so probably not short of other offers.
Plus - though you might have missed it - he's now attached to a second TV series, the thriller StartUp on streaming service Crackle (it's like a less-famous Netflix).
"I honestly don't know if there will be any more. It's incredibly difficult to get Benedict and Martin's diaries to align," Gatiss said.
"It's a nightmare to schedule," he reiterated in July 2017."It was very, very hard to schedule the last series, because of Martin [Freeman] and Benedict [Cumberbatch]'s availability. And Steve [Moffat]'s and mine.
"There is always that Fawlty Towers principle of, 'Let's just leave it'."
Could scheduling prove to be Sherlock's greatest enemy? Moffat will be giving up his showrunner duties on Doctor Who as of 2018, but he's spoken of his desire to work on an original project in the near future.
The recent announcement of Dracula - a new series from Moffat, Gatiss and Sue Vertue's Hartswood Films, could also present a potential obstacle.
For the past seven years, Moffat has been heading up two high-profile TV series in Doctor Who and Sherlock and doesn't sound particularly keen to undertake a similar challenge again in future.
"I'm just at the end of my toughest ever year in which I'll have done... three Sherlocks and 14 Doctor Whos," he told Radio Times. "That's been shattering."
So juggling both Dracula and Sherlock? Probably not a prospect he'd thrill to – even if Benedict Cumberbatch and Martin Freeman were to suddenly become available.
Sherlock season 5 episodes: Which stories could be adapted?
Don't think that Moffat or Gatiss are spent when it comes to Sherlock, though - "there are ideas" which the pair are still hoping to tackle in future.
"There's an element of 'The Greek Interpreter' that I think is really exciting, which hasn't been done, because in our version of events Irene Adler is still out there. There's always that."
While the show very much forges its own path, it's always been at least part-inspired by Conan Doyle's original stories - many of which have already been adapted, or at least touched upon, since 2010.
His four full-length Holmes novels have been cannibalised - 'A Study in Scarlet' as 'A Study in Pink', 'The Sign of the Four' as 'The Sign of Three', 'The Hound of the Baskervilles' as 'The Hounds of Baskerville' and 'The Valley of Fear' as 'The Blind Banker'.
But many short stories are still more or less untouched, including... *deep breath*
- 'The Red-Headed League' - Holmes and Watson look into strange happenings involving a group of exclusively red-haired men. Gatiss had originally planned to adapt this story for series four.
- 'The Boscombe Valley Mystery' - When a man is murdered, his blood-covered son stands accused. But Holmes has his own theory.
- 'The Man with the Twisted Lip' - Trailing a missing man, Holmes enters one of London's vilest opium dens.
- 'The Adventure of the Blue Carbuncle' - Sherlock must solve a case where the only clues are a Christmas goose and a hat... potential festive special?
- 'The Adventure of the Engineer's Thumb' - A young man with severe injuries and a chilling tale arrives at Watson's surgery.
- 'The Adventure of the Noble Bachelor' - When a missing bride's clothes appear in a lake, Sherlock is called upon to unravel her disappearance.
- 'The Adventure of the Beryl Coronet' - Holmes investigates the theft of stolen jewels from one of the treasures of the Empire. (Too similar to Moriarty pinching the Crown Jewels?)
- 'The Adventure of the Copper Beeches' - A young governess consults the detective after being made an enticing offer - but what's the catch?
- 'The Adventure of Silver Blaze'- Holmes heads to Devon, when a racehorse favourite disappears and his trainer is found murdered.
- 'The Adventure of the Cardboard Box' - A parcel containing two severed ears - a macabre prank or, as Holmes believes, evidence of a serious crime?
- 'The Adventure of the Stockbroker's Clerk' - Our heroes probe the mystery company behind a young man's offer of a dream job.
- 'The Adventure of the Reigate Squire' - Burglary and violent death among the Surrey gentry, as Holmes tries to convalesce from over-work.
- 'The Adventure of the Crooked Man' - Holmes looks into an officer's death, with the regimental honour of the Royal Mallows at stake.
- 'The Adventure of the Resident Patient' - A doctor calls at 221b Baker Street after the mysterious death of his landlord.
- 'The Adventure of the Norwood Builder' - Sherlock takes up the case of a young solicitor accused of murder.
- 'The Adventure of the Solitary Cyclist' - Who is stalking music teacher Violet Smith?
- 'The Adventure of Black Peter' - The grisly murder of a retired whaling skipper provides a baffling new case.
- 'The Adventure of the Three Students' - Sherlock casts his eye over the theft of important exam papers. (It's more exciting than it sounds.)
- 'The Adventure of the Golden Pince-Nez' - The sleuth tackles a motiveless murder, with just a pair of specs and the victim's dying words to go on.
- 'The Adventure of the Missing Three-Quarter' - Sherlock does sports, investigating when a vital player disappears on the eve of an Oxford v Cambridge rugby match.
- 'The Adventure of the Abbey Grange' - Inspector Hopkins blames burglars for the murder of one Sir Eustace Brackenstall, but Holmes is not so sure.
- 'The Adventure of the Second Stain' - The Prime Minister asks Sherlock to recover a letter vital to national security.
- 'The Adventure of Wisteria Lodge' - Voodoo rituals and mystery disappearances form a gruesome riddle.
- 'The Adventure of the Red Circle' - Worried about her strange lodger, a landlady calls on the great detective for help.
- 'The Disappearance of Lady Frances Carfax' - Watson heads to Switzerland for a missing aristocrat, but the trail leads back to a funeral parlour.
- 'The Adventure of the Mazarin Stone' - Holmes puts his life on the line to trap an audacious jewel thief.
- 'The Problem of Thor Bridge' - A beautiful young governess is accused of murder... sounds like a case for the Baker Street boys!
- 'The Adventure of the Creeping Man' - Holmes applies his skills to the bizarre behaviour of a distinguished scientist.
- 'The Adventure of the Sussex Vampire' - Sherlock's powers of deduction and reason are challenged... by creatures of the night?
- 'The Adventure of the Three Gables' - When a young diplomat dies in Rome, Sherlock turns to the tabloid press for help.
- 'The Adventure of the Blanched Soldier' - While Watson is away, his friend takes on the case of a Boer War veteran.
- 'The Adventure of the Veiled Lodger' - Holmes questions a mysterious tenant who refuses to show her face.
- 'The Adventure of Shoscombe Old Place' - Sherlock and Dr Watson make a gruesome discovery in an old crypt.
So yeah... plenty to be getting on with there, and it's also possible that the series could forge its own path, with Sian Brooke voicing her desire to return as Sherlock's sister Eurus Holmes - a character unique to the television series.
"I definitely think there's more to explore with her," Brooke said. "I hope that she wouldn't become a softie. There's a lot of fun to be had in playing somebody that cold and calculating."
Sherlock season 6 and beyond: What does the future hold?
With so many stories yet to tell, far from being done, Sherlock could have a long future ahead of it... but will it be on television?
With 90-minute episodes already screening in cinemas, it wouldn't be a huge leap for the show to spin off into a bona-fide motion picture.
Cumberbatch has acknowledged that a film is one of the options going forward, along with another series on TV in "a few years' time" being possible, as well as "one-offs".
He did, however, add: "In the past when I've done anything that's had a success in its original format, the idea of then transposing it always scares me a little bit."
Whatever happens, whichever medium Sherlock finds itself in, you can be sure of one thing - Moffat and Gatiss have no plans to hand the franchise over to a new creative team.
"Of course, loads of other people will do Sherlock Holmes and we'll be the first people to watch those," Moffat has said. "But our version is our version."
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