There's a mummy coming and the victim only has 66 seconds to live! The brief of "do an Egyptian mummy on an Orient Express in space" might have been given to Mathieson by Moffat but it was ultimately Mathieson who made the episode shine. Every element works, from the train captain with a secret to the homicidal computer, Gus. The CGI for the mummy creature is also extremely effective, as is the CGI for the space train. When these story elements and effects are combined with great acting, good sets and nice costumes, the result is an absolute corker. From the opening tease of the mummy killing its victim to the final scene in which the Doctor scribbles in the sand of a beach whilst Clara sleeps, there is nothing to change, nothing to fix. Indeed, as with Listen, there are only things that disappoint because they weren't explored further in subsequent stories, like the nature of the Doctor's scribbles, and that is a sin committed by others, not Mathieson. What do you think of this ranking? Do you agree/disagree? As always, leave your rankings in the comments section below.