How to follow on from an episode like Rosa was always going to be a tough question. You could try and match its ambition, but that would be tricky. Your episode risks looking weak if you can't match its predecessor's impact or - perhaps worse - risks undermining that impact. You could go the complete opposite route and do a Dinosaurs on a Spaceship / Robots of Sherwood style silly episode. However, this shift in tone would likely feel jarring and a good silly episode is not an easy feat. With little ambition beyond filling time with some fun, it has to be really fun to overlook its relative lack of substance. Or, you can do what Arachnids in the UK did and keep it simple with a good old-fashioned scary episode. Arachnids in the UK naturally picks spiders as its monster of choice. Of course, this being Doctor Who , these aren't just any old spiders. They're giant, human targeting spiders with a mysterious origin. There are some delightfully thrilling moments with t...