A new PBS trailer provides some clues about Sherlock‘s long-anticipated and well-guarded one-off special set in Victorian times. Benedict Cumberbatch returns as Sir Arthur Conan Doyle’s hyper-perceptive sleuth, along with his Baker Street flatmate Dr. John Watson (Martin Freeman). The pair trade in their modern trappings for a ghostly trip in the wayback machine to the 19th century, complete with deerstalker cap (for Holmes) and handlebar mustache (for Watson). The program is airing stateside under PBS’ venerable Masterpiece banner.

A teaser released for Comic-Con in July contained a typically wry tidbit from the master detective. When his landlady Mrs. Hudson (Una Stubbs) fusses that she wishes Holmes would let her know when he’s returning home from a trip, he replies: “I hardly knew myself, Mrs. Hudson. That’s the trouble with dismembered country squires — they’re notoriously difficult to schedule.” The new trailer doesn’t provide much more information, aside from a very dark tonal shift that makes Holmes’ social awkwardness — somewhat charming in the modern incarnation — feel positively creepy. And nope, no sign of Moriarty.

The Sherlock special also will be released in theaters, but still no PBS premiere date. Have a look-see, and tell us what you think.