BBC One's "Sherlock" has been a hit since its debut in 2010, but with its lead stars so busy with their own schedules, fans of the show have to wait two years before the next season arrives. Indeed, it has been almost a year now since season 3 aired and there's still another year of waiting until season 4 arrives. But when "Sherlock" returns in 2016, fans can expect to receive three brand new episodes, plus a one-off episode as an early treat.

Obviously, viewers want to be served more than three episodes after waiting for two years. Reports say that fans are blaming Benedict Cumberbatch's busy movie schedule for the lack of episodes for the TV series. But that's how it's always been since the inception of the show, with only three episodes each, shown in 2010, 2012 and 2014. On the other hand, fans will be treated to a one-off episode that will air around Christmas of 2015.

Meanwhile, with everyone waiting for some "Sherlock" season 4 news, there are numerous speculations going around about what's to come. The first is that Dr. Watson's wife Mary Morstan might die in the new season.

Steve Moffat, creator of "Sherlock," told Entertainment Weekly, "We have a plan to top it. And I do think our plan is devastating. We've practically reduced our cast to tears telling them the plan ... we're probably more excited that we've ever been about Sherlock."

Immediately, fans began speculating that it will be Morstan who will meet her demise.

Other spoilers for season 4 include the return of Irene Adler. Adler is Sherlock's former love interest, and she is a very interesting character.

Actress Lara Pulver shared to RadioTimes, "Sherlock is Mark Gatiss and Steven Moffat's passion project. If it fits to have her back, I know they'll write it; if it doesn't, I trust them to get it right."

Another love interest for Sherlock, Janine, is rumored to be returning, too.

According to Moffat, "He likes her, though. He'll see her again. They'll be pals. I loved Yasmine's performance as Janine -- she still likes him in the end. She'll be very cross with him, but she'll show up, and they'll have a good time. They will, because he likes her."

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.