Writer Mark Gatiss went back to his Northern roots for this Yorkshire set episode in which iconic Yorkshire actress Dame Diana Rigg not only gets to use her native accent for once, but also appear alongside her daughter. Gatiss' grim oop North script riffs off Sherlock Holmes, understandably given his other collaboration with Moffat, and real social, industrial history to create a mystery around strange goings on at a Saltaire-esque model community. Inspired by the "repulsive story of the red leech" referenced but never further described in the original Holmes stories, The Crimson Horror is a decent mash-up of mystery and Gothic with the fact that the Doctor is sidelined for much of the early part of the episode giving the supporting cast a chance to shine. Sonataran butler Strax's once amusing shtick is becoming a little tiresome and there is a particularly lame GPS gag, but the episode does develop the character of Jenny into a far more interesting and adventurous one than in her previous mostly sidekick-centric appearances. The real draw here, though, is Rigg. Gatiss wrote the part of the villainous Mrs. Gillyflower, who is in a bizarre symbiotic relationship with a poisonous red leech, specifically for the Game of Thrones star on discovering that she had never acted opposite her daughter Rachael Stirling. The existent family dynamic gives extra weight to the twisted relationship between Mrs. Gillyflower and her blind daughter Ada, played by Stirling, while Rigg is clearly having a ball playing such an evil character.
