'Sherlock' season 4 spoilers, plot news: Moriarty comes back to life? Early 2017 release

Sherlock Holmes is coming back. 

According to Wales Online, the fourth season of "Sherlock" is set to be filmed in spring and will be shown next year. The scenes will be shot at Pinewood Studio Wales on the outskirts of Cardiff at Wentloog and in South Wales. 

"We are going to try too take it somewhere we've never been before – and I don't mean outer space," Mark Gatiss, writer and co-producer, told Entertainment Weekly back in August 2014 as they discussed season 4. "We always start with a re-introduction that builds toward a darker climax – we might just be going darker [from the outset]. We got a very, very good set of ideas."

Benedict Cumberbatch will return as Sherlock Holmes, while Martin Freeman will be returning to play the role of Holmes' sidekick, Dr. John Watson. Moriarty, the worst enemy of Holmes, is also speculated to be alive and will be included in the new series.

In the last part of season 3, Moriarty appeared and asked, "Missing me?" With this statement, people are speculating that the baddie could have faked his death and would be re-appearing in the new season. 

There are also speculations that a new character will be introduced. The third brother of Holmes, Sherrinford, might appear and is said to be played by Tom Hiddleston. 

A video claiming to be an official trailer posted by Sherkology also shows some hints about the new episodes. It flashes phrases like, "The most dangerous criminal mind the world has never ever seen," "End is soon," "With more chaos," plus a collage of words like "Gruesome, baffling, high treason, self-sacrifice, fraud, heartache, sentiment, blood, conspiracy, and murder."

"Sherlock" series 4 is expected to be shown in 2017.