"Sherlock" season 4 is coming this year. Will spring bring Moriarty back? Find out what else is in store as production begins in South Wales.

"Sherlock" fans' long wait could be soon over as cast and crew is reportedly settling down in Pinewood Studios - the famous set that housed "Doctor Who" and "Star Wars: The Force Awakens."

Benedict Cumberbatch will don the detective hat once again as Sir Arthur Conan Doyle's Sherlock Holmes with Martin Freeman as his reliable sidekick Dr. John Watson. The two are expected to be filming on the outskirts of Cardiff this spring.

The plot thickens as Sherlock's sworn enemy is said to be alive and coming back. News are spreading like wildfire when fans noted red herrings written all over the "Abominable Bride" episode where Mycroft is seen writing down words like "Redbeard," "611174," and "Scarlet Roll." These are infamous names in the Sherlock novels but there could be a twist behind this season.

The team behind this season remain tight-lipped, however, writer and producer Mark Gatiss announced to fans that they are working quite hard to make this season better than the previous seasons.

"We're going to try to take it somewhere we've never been before - and I don't mean outer space," Gatiss explained to Entertainment Weekly. To give viewers some perspective to what they can expect out of this season, he describes the plot as having a darker climax and it will continue to get darker.

That could be a twinkling in the night which might mean that this season will be intense and teases fans that Moriarty could be coming back. If arch rival Moriarty, played by Andrew Scott, does come back after taking his own life in season 3, then this will surely make fans anxious and excited.

Stay tuned for more "Sherlock" season 4 here!