Without further ado, the cast and crew of "Sherlock" have begun filming season 4. BBC hasn't made an official announcement about the production kick-off, but numerous evidences have emerged hinting that Benedict Cumberbatch and Martin Freeman are back to work as Sherlock Holmes and his loyal companion John Watson, AceShowbiz reports.

On early Tuesday, April 5, Freeman's real-life partner Amanda Abbington who also stars as John's wife Mary Morstan shared on Twitter a picture of the script. "Let's do this then. #Sherlock #setlock," she captioned it without further explanation.

Meanwhile, a fan who passed by Cardiff Bay noticed what appears to be trucks of the filming crew parked on the streetside. "Walking to work (Cardiff Bay) and passing what is likely to be #Setlock #Sherlock," she wrote along with the photo.

Details of the upcoming season of the British drama series are not available yet. Previously, co-creator Mark Gatiss teased that season 4 would be coming soon with a picture of a skull wearing bizarre glasses seemingly in Sherlock's famed 221 Baker Street residence. "I spy Series Four...#Sherlock," he wrote in the caption.