Sherlock is back, but it’s not exactly the same as the modern retelling of the story you might be familiar with. Instead, the BBC‘s upcoming Christmas special takes us to Victorian London where the original stories by Sir Arthur Conan Doyle were set. Check out the first trailer above.

The short teaser, which was released this week at San Diego Comic-Con, focuses more on humor than mystery. That’s fine by us, though we’re more than a little curious what Dr. John Watson is hiding inside his mysterious box.

We open on the Baker Street address, where Holmes and Watson have lived in past seasons, before panning out to reveal a street full of horse-drawn carriages instead of the usual cars. Watson also gets a chance to explain his period-appropriate new mustache during a quick conversation with their landlord Mrs. Hudson.

We don’t get much of a hint at the actual plot, though the new episode of Sherlock can seemingly do pretty much whatever it wants without worrying about continuity with the rest of the series. That’s one key advantage of setting this episode in another century. Based on the IMDB page for the upcoming special, it also looks like the villainous Jim Moriarty will make an appearance.

The new episode is set to arrive in December 2015, so you can probably expect plenty more teasers and news before then. For now, check out some screenshots from the first trailer below.