Peeks from the 'Sherlock' season 4 set (pictures)

The cast and crew of "Sherlock" season 4 have been keeping fans guessing with photos tweeted from the set. Sherlock Holmes (Benedict Cumberbatch) has returned to a new case. But are those new curtains in his flat at 221B Baker Street as well?

How many items can you name on Sherlock Holmes' messy desk?

Not only has Sherlock Holmes returned, but it looks like Dr. John Watson (Martin Freeman) is back as well.

New "Sherlock" episodes mean a new director. Say hello to Rachel Talalay sitting in Sherlock's favorite chair.

"Sherlock" Production Designer Arwel Wyn Jones gives a close-up of Holmes' favorite skull.

If only we could get a look inside this "Sherlock" season 4 script.

"Sherlock" wouldn't be the same without his smitten forensic pathologist, Molly Hooper, played by Louise Brealey, who tweeted this photo.

Vintage dolls are always kind of creepy. But this photo tweeted by "Sherlock" actress Louise Brealey makes them even more shiver-worthy.

No need to wait for Mrs. Hudson to let you inside Sherlock's flat. His door already appears to be open.

Some props from the "Sherlock" set are more cryptic than others. Here's hoping an automaton villain is in the works.

"Sherlock" co-creator and actor Mark Gatiss looks rather eager to get started shooting season 4.