Episode 2 of Series 7, Part 2 takes us all the way back to the late summer of 1981 and a serendipitous encounter between a red leaf and young couple-to-be; reveals that time is not, point of fact, made of strawberries; and pits the Doctor against his biggest—some might even say most awesome—enemy yet...

Written by show-runner Steven Moffat, the Series 7, Part 2 opener finds the Doctor and his TARDIS holed up in a monastery in Cumbria, circa 1207. Mad to solve the mystery of Clara Oswin Oswald, the Doctor has, at another's suggestion (see "The Bells of Saint John: A Prequel"), "withdrawn to this...