"The stage is set. The curtain rises. We are ready to begin," Sherlock says in the ominous new trailer for Sherlock's upcoming Victorian-era-set special.

There's still no date for the standalone installment, or any indication of exactly how or why Sherlock (Benedict Cumberbatch) and Watson (Martin Freeman) are back in 19th century London, but we do finally get a lengthy preview of the famed detective's new (or old?) mission, which supposedly has something to do with ghosts. Take a look at the preview of some dangerous action, a mysterious "something" that is no longer safe, and Watson's latest frustration with Sherlock.

"You're Sherlock Holmes, wear the damn hat," he grumbles, handing over a deerstalker.

We also get glimpses of a mutton-chop-wearing Lestrade (Rupert Graves), John's wife Mary (Amanda Abbington) and a bunch of people in dark robes and pointy conical hats. Creepy much?

Are you looking forward to the new Sherlock special?