Benedict Cumberbatch
Actor Benedict Cumberbatch smiles as he arrives at the 2014 Vanity Fair Oscars Party in West Hollywood, California March 3, 2014. Reuters/Danny Moloshok

It has now been officially confirmed that BBC has ordered "Sherlock" Season 4. Also, the producers of the hugely popular T.V. series have confirmed that in addition to the three episodes of the season, there is a special, bonus episode, as well. Martin Freeman had hinted about this special episode in one of his interviews. The new season of "Sherlock" promises to take the two principal characters into deeper and darker water.

"#Sherlock, the hit @BBCOne drama, will return for a Special, followed by a series of three new episodes. #221back," BBCONE shared on Twitter. "Series Four! At last ! It's always special to return to Sherlock but this time it's even more special as we're doing... a Special!" Mark Gatiss, co-creator of the show, also confirmed the news about the special episode.

The shooting of the special episode is scheduled to begin in Jan. 2015. BBCONE tweeted, "We're ready to unleash the most shocking and surprising series of #Sherlock yet. The only thing is to expect is the unexpected... #221back."

Gatiss has said that the new season of the show will take Sherlock and Dr John Watson "into deeper and darker water than ever before." Steven Moffat, co-creator of the show, added that "... we're reasonably confident that the very next thing to happen to Sherlock and John, is the very last thing you'd expect..."

The shoot of the three episodes is expected to begin later next year. There may be a delay in the announcement of the shooting schedule because of Benedict Cumberbatch and Martin Freeman's busy acting schedules.

"It's taken a little while to get the dates sorted as none of the boys are 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," said Sue Vertue, executive producer at Hartswood Films.

As the filming will begin in 2015, it can be very much expected that "Sherlock" Season 4 is likely to premiere in 2016.