• Actor Benedict Cumberbatch attends the media day at the Chelsea Flower Show in London May 19, 2014.

Actor Benedict Cumberbatch attends the media day at the Chelsea Flower Show in London May 19, 2014. (Photo : REUTERS/Stefan Wermuth)

"Sherlock" Season 4 will bring new challenges for the iconic detective Sherlock Holmes (Benedict Cumberbatch) and his friend John Watson (Martin Freeman). The enormously popular BBC's detective series will be returning with its Christmas special before it kicks off Series 4. The airdate for the fourth instalment of "Sherlock" is yet to be revealed. However, the co-creator of the show is already spilling details about it.

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In his latest interview with Entertainment Weekly, Steven Moffat revealed that Sherlock and Watson have dark times to face in future. Fans can expect to see some suprises as "Sherlock" Season 4 will reportedly unveil answers to questions that "nobody has asked" until today. Moffat said that he and co-producer Mark Gatiss has "set up something" that he refuses to reveal the details about.

When asked to compare the upcoming season with previous instalments, Moffat revealed that they are yet to pen down the episodes. But the upcoming season will be about "consequences," said the show's creator.

"Chickens come to roost. It's dark in some ways-obviously it's great fun and a Sherlock Holmes romp and all that-but there's a sense of... things... coming back to bite you," Moffat explained. The showmaker assured that "Sherlock" will continue to be funny. However, sometimes it may get "bloody frightening."

Just like any other "Sherlock" in previous years, Season 4 will also feature three stand-alone stories of 90 minutes each. At the same time, an ongoing mystery will continue to play in the background. Moffat assured that Season 4 will leave fans "desperate for Season 5."

In the rest of the interview, Moffat talked about different aspects of making the show, keeping Cumberbatch and Freeman interested in the role with newer challenges, killing Moriarty and the show's budget. The series maker even talked about the highly anticipated "Doctor Who" and "Sherlock" crossover. Moffat disclosed that he is ready to give fans what they want. However, his colleagues reportedly think tie-in won't be a great idea.

Before Cumberbatch and Freeman reprise their roles of the iconic detective duo for Season 4, the actors will make a return for Christmas special. Speaking at a panel at the South by Southwest conference (via EW), Moffat confirmed that the upcoming episode will be set in Victorian London and will take fans 100 years back in time.