"Sherlock" Season 4 is returning to the BBC early in 2016. Fans need not dispair as there is a Christmas special planned to air 2015.

One of the more prevasive rumors is that Tom Hiddleston will join the cast for season 4, Christian Today reports, "The cherry on the cake is the rumor that Tom Hiddleston will be part of the new season. This rumor started when Mark Gatiss joked about considering Hiddleston for a role in the TV series." Though it started as a joke it has fast become a favorite fan rumor.

The latest speculations are that Mary Morstan will die, which happens in the books, and has become an especially popular theory in light of recent interview with Britain's Radio Times, "Sherlock" co-creator (and the actor behind the detective's enigmatic brother Mycroft) Mark Gatiss teased, "you can always expect tragedy as well as adventure" when the critically acclaimed show returns.

Martin Freeman said to The Telegraph, "While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did. So [Watson] gets married, and then Mary dies - so at some point presumably she'll die."

In recent news Benedict Cumberbatch has told Vogue, that "If we can keep the quality up," he says of the show, "I can't imagine that I will ever get tired of being Sherlock. I'd love to play him as an old man." This alleviates many fans concerns that Cumberbatch will leave the show. Season 4 isn't even scheduled to start shooting until the summer of 2015 due to Cumberbatch and Martin Freeman's busy schedules.

BBC has released a teaser photo of the script for the Christmas special.

In other news, Showrunner Steven Moffat recently shared some insights about the possible return of Moriarty, "That was [decided] in the cutting room," said Moffat to the Digital Spy. "It was Mark [Gatiss]'s idea to get one more little blip of him, and we shot the live action shot which we hadn't done for the actual show and put that in after the credits. It was just a final little treat, really, to wind people up!"

"I can't really say what we're doing with that, but there is no last-minute whim in this," said Steven Moffat to Vulture when asked about the new twist. "We've had what we're going to do with Moriarty in place from before the second season. Exactly what we're going to do. I remember talking it through with Andrew Scott, who plays Moriarty. Wait and see what's going to happen

But Gatiss won't be drawn on whether that tragedy will include the death of John Watson's wife Mary, played by Martin Freeman's real-life partner Amanda Abbington.

Freeman himself has suggested she'll be killed off "at some point", because that's what happens in Sir Arthur Conan Doyle's Sherlock Holmes stories.

"While we play fast and loose with the original stories, we generally follow the trajectory of what Conan Doyle did," Freeman told The Telegraph earlier this year. "So [John] gets married, and then Mary dies - so at some point presumably she'll die."

But Gatiss says viewers should assume nothing.

"Just because it's in the stories doesn't mean it'll happen in the series because there's an awful lot of changes and an awful lot of places to go and things to do," he says.

"It should be clear by now that while, of course, Doyle is our absolute god, we have gone quite a long way away as well - we've introduced Sherlock and Mycroft's parents [for instance], I don't think they've ever been seen in any adaptation - so there are lots of surprises to come.

In a recent interview Benedict Cumberbatch revealed some new information about season 4.

"You find out about Sherlock's background," the actor said. "You find out that he comes from a truly stable home. It was a gesture in the first episode, but you see that in practice in the third. You see that, as a boy he was deeply insecure -- it begins as a taunt [from his older brother, Mycroft] ... and that comes back to haunt him and he feels like a child. He's reduced to feeling like a child."

"Immediately as an actor I wanted to understand who [Sherlock] was, what his parents were," he said. "These were questions I asked. ... I wanted to understand. [Moffat] was just talking about, 'Can't this guy just be good at what he does and he's your age and he looks like you and he's doing his thing?' And I went, 'No, no, Steven. There's a process I've got to go through. I've got to understand how I became this person.' "

"I can't just sort of float onto set with a whole bunch of mannerisms and hope it sort of comes off. You have to ground it in some sort of reality, otherwise you get found out as things sort of evolve."

"And [Moffat] said, 'But can't he just be really good? Can't he just be good at it? Why does he have to have flaw or an Achilles' heel?'" the actor said. "Because I said, you know, 'Where's his weakness?' Because no human being doesn't [have one]. And however much [Sherlock] tries to convince himself he's not human, he is."

According to writer and director Steven Moffatt, "Benedict and Martin [Freeman] are making some movies. If you say 'Who cares about movies?' I agree with you, but they are doing them so we've got to schedule around that," Bustle adds. Speaking of movies, Benedict Cumberbatch took on the role of Doctor Strange, do you think it will effect the filming for Sherlock. In a strange round about, Tom Hiddleson (who plays Loki for Marvel) has also been rumored to be playing the third Holmes brother, Sherringford.

Mark Gatiss has said that they have, "Moved significantly closer to getting a date in the diary for series four."

Cumberbatch will act in "The Imitation Game," "Penguins of Madagascar," "The Hobbit: The Battle of Five Armies," "Black Mass," "Magik," "The Yellow Birds," "Jungle Book: Origins" and "Flying Horse" before he returns to Sherlock.

Martin Freeman is also working on "The Hobbit" and FX's Fargo.

Steven Moffat, the show's co-creator stated that the fourth season of the show will certainly be bigger and better than the previous one. It would even possibly top the epic finale of the 3rd season, with Moriarty, returning from beyond the grave.

In an interview with Hollywood Reporter, the co-creator said;

"We practically reduced our cast to tears by telling them the plan. Honestly, Mark [Gatiss] and myself are so excited with what we've got coming up, probably more excited than we've ever been about Sherlock. ... Honestly I think we can [top the last series]."

The BBC has yet to make any official statement, but the Christmas Special is rumored to be based on the story of "The Adventure of the Blue Carbuncle".

E News reports that Moffat, when Speaking about topping season 3, said, "We have a plan to top it. And I do think our plan is devastating,' he replied.

At the HBO after-party, fellow Sherlock writer-producer and actor Mark Gatiss teased a little more about season 4: "We're going to try to take it somewhere we've never been before - and I don't mean outer space," he said. "It will be challenging place to go. We always start with a re-introduction that builds toward a darker climax - we might just be going darker [from the outset]. We got a very, very good set of ideas."

As previously reported, Seaosn 4 will be coming in 2016, and the BBC has greenlit a Christmas special to come before that, it is reportedly based on "The Blue Carbuncle."

Co-creator and co-show runner Mark Gatiss confirmed this as well, saying "[We] moved significantly closer to getting a date in the diary for series four."

'What has been explained to me and Ben [Cumberbatch] and Amanda Abbington - my missus who plays Mary - has been very exciting,' he continued.

Speaking about the return of Janie (the girl Sherlock got along with at the wedding) and Irene Adler

Of course, the woman whom the sleuth had a romantic interest with, Irene Adler (Lara Pulver) was also rooted to return. But series co-creator Mark Gatiss implied that it won't happen so.

"The danger is you have a successful character like Irene Adler and she makes a massive impact because that story is so perfect, but if she then moves in around the corner, it becomes a bit cozy," Gatiss told Digital Spy.

"Sherlock" three-episode Season 4 is expected to air in early 2016 following a Christmas special in 2015.

'The plans they have got for the overarching series - oh man, it's just so exciting!' he told BBC Radio Wales.

So lets do some creative/ speculative back tracking. One thing we know for sure is that Mary Morestan was pregnant at the end of last season, so expect a baby and all the drama that comes with it. We also know that they stick somewhat to the books, in which Mary Morestan dies, and that this season is going to be "devestating." So, best guess, would be the devestating plan Moffat is talking about involves the death of Mary Morestan.

Check back for more Sherlock Sesaon 4 spoilers as they become available.