And Mark Gatiss has given us the title for Episode 1!

So here we have it: The Empty Hearse:

We've known for a while that episode 1 would be based on The Adventure of the Empty House - the first Conan Doyle story written after fans demanded the Great Detective's return, as well as the story that introduces Colonel Sebastian Moran, Moriarty's most dangerous Henchman - but now we have a twist to the title. Could it be a reference to Sherlock's escape from death at the end of The Reichenbach Fall?

So we have a title, and our three clue words - Rat, Wedding, and Bow - there's not much we can do but wait to find out more...