Fancy a prequel to this year's Doctor Who Christmas special, The Snowmen?  Well, you're in luck.

This video, titled Vastra Investigates, introduces three characters who are set to appear in the Christmas Day episode - Madame Vastra, Jenny Flint and Commander Strax. 

The mini-episode, which is just over two and a half minutes long, sees Vastra and Jenny helping Scotland Yard to tie up a complicated investigation, before the pair discuss the disappearance of the Doctor and refer to the demise of Amy and Rory Pond.

Jenny says: "Still no word from The Doctor, then?... He can't sulk in his box forever"

While Vastra replies: "Heartbreak is a burden to us all - pity the man with two." 

The end of the tantalising video hints to the snowy Christmas special. Jenny notes that it has begun to snow before a concerned Vastra realises that there aren't any clouds in the sky for the snow to be falling from... 

The Doctor Who Christmas special is on Christmas Day at 5:15pm on BBC1