"Sherlock" cast Benedict Cumberbatch to return to BBC for the fourth season of the hit show. Creator Steven Moffat promised three new episodes plus a special stand-alone episode.

According to Variety, the production for "Sherlock" special episode will begin in January 2015. The three other episodes will start later next year.

"It's a record-breaking run! Of course, it's far too early to say what's coming, but we're reasonably confident that the very next thing to happen to Sherlock (Benedict Cumberbatch) and John (Martin Freeman) is the very last thing you'd expect," he told the magazine.

Co-creator and writer Mark Gatiss said that "Sherlock" cast Benedict Cumberbatch will be able to play with the character because they will take the genius detective and his loyal friend John Watson "into deeper and darker water than ever before."

"The whole 'Sherlock' team are terrifically excited to return for four new adventures. The game is on - again!" he said.

Sue Vertue, executive producer of Hartswood Films, admitted that it took a little while "to get the dates sorted."

"None of the boys is exactly sitting back twiddling their thumbs but there was unanimous goodwill to make this work, so we're thrilled that 221b is going to be inhabited again," she said.

"The Hobbit" cast Martin Freeman, in an interview with London's Telegraph said "Sherlock" cast Benedict Cumberbatch will return on the small screen for the series special by Christmas next year.

"If that's going to be a special, I'm speaking off-message here, if this was New Labour I'd get fired - I think that might be for next Christmas. A Christmas special. That's what I understand," said Martin Freeman, who plays Dr. Watson.

In the same interview, Martin Freeman revealed they don't really stick to Sir Arthur Conan Doyle's source material.

"[But] we generally follow the trajectory of what Conan Doyle did. So he [Watson] gets married, and then Mary dies - so at some point presumably she'll die," Martin Freeman added.