BBC Worldwide has released the official synopsis and five new images for the Victorian-set "Sherlock" special "The Abominable Bride."

While they don't provide any answers as to how the episode takes place in 1895 London, they do offer new looks at Watson's mustache and Lestrade’s muttonchops, and some clues to the central mystery, involving  "an enemy seemingly from beyond the grave":

We've been here before - but what if this wasn't the modern day but the late Victorian period? What if the world's most famous consulting detective and his best friend lived in a Baker Street of steam trains, hansom cabs, top hats and frock-coats?

Welcome to 'Sherlock' in 1895!

Some things, though, remain reassuringly the same. Friendship, adventure and especially, MURDER...

Why is Thomas Ricoletti a little surprised to see his wife dressed in her old wedding gown? Because, just a few hours before, she took her own life...

Mrs Ricoletti's ghost now appears to be prowling the streets with an unslakeable thirst for revenge. From fog-shrouded Limehouse to the bowels of a ruined church, Holmes, Watson and their friends must use all their cunning to combat an enemy seemingly from beyond the grave and the final, shocking truth about... the Abominable Bride!

Starring Benedict Cumberbatch and Martin Freeman, "Sherlock: The Abominable Bride" will premiere Jan. 1 on PBS and BBC One, and in select theaters.