'Vastra Investigates' by Steven Moffat

England, 1842: once again Madame Vastra, Jenny and Strax help Scotland Yard to solve a seemingly impossible case, this time involving identical twins, poison undetectable to science and an ancient Egyptian curse. As Strax escorts the handcuffed culprit away, the police inspector stops to thank Vastra, and is somewhat surprised to learn that instead of suffering from a skin condition she is in fact a member of an ancient race of intelligent reptiles, who was woken from her slumber by construction work on the London Underground – and he is even further taken aback to hear that Vastra is in love with her assistant, Jenny. Departing in their horse-drawn carriage, Vastra and Jenny muse over the lack of contact from the Doctor, who is currently away in his TARDIS, sulking over the loss of Amy and Rory; however, their conversation his interrupted by the sight of snow falling on the street outside – even though there are no clouds in the sky…

Matt Smith (The Doctor), Neve McIntosh (Madame Vastra), Catrin Stewart (Jenny Flint), Dan Starkey (Commander Strax), Paul Hikey (Inspector Gregson)

Directed by Saul Metzstein
Produced by Marcus Wilson
Executive Producers Steven Moffat and Caroline Skinner
A BBC Wales production

Notes:
*Featuring Madame Vastra, Jenny and Commander Strax, and the Eleventh Doctor

*This specially-made two-and-a-half-minute prequel to 'The Snowmen' was made available on the BBC's official 'Doctor Who' website