(W) Robbie Morrison (A) Rachael Stott (CA) Claudia Caranfa. Can the Twelfth Doctor unravel the mystery of 'The Talons of Quetzalcoatl'? From the mean streets of 1920s San Francisco to a reality-shaping serpent of myth* we close out Year Two with a two-part film noir gumshoe horrror spectacular that's packed full of surprises!