It has been confirmed that the production will start filming in Morocco, though the details on the filming is still scarce.

According to Metro, the fourth season of the mystery series will have some scenes filmed in Morocco. However, it is still unclear as to where the storyline of Benedict Cumberbatch and Martin Freeman will lead.

The filming of the first episode reportedly has been completed and the second one is still in works. The filming of the first episode was done in Cardiff, Wales, and seems that some the third or the fourth episode will be shot in Morocco, according to Ecumenical News.

Meanwhile, it is also confirmed that Toby Jones will be joining the cast of "Sherlock" as a mysterious villain. Jones has starred in a number of British shows like "Detectorist" and "The Secret Agent". His voice was also heard in several "Harry Potter" movies.

On the other hand the series co - creator Steven Moffat was delighted to introduce Jones in the series. "Delighted to have Toby Jones on board, bringing to life one of [Sir Arthur Conan] Doyle's finest villains," he said, according to Deadline.

While Cumberbatch and Freeman will be positively returning in the upcoming season, with Amanda Abbington (as a pregnant wife), rumors are also in the air about Tom Hiddleston joining the cast as Sherrinfold Holmes. Even creator Mark Gatiss also mentioned that they would love to have the "Avengers" star on board.

However, with Hiddleston's hectic schedule, it would be hard for him to join the cast.

"Sherlock" season four is slated to be on air in January 2017.