Scotland, monsters, Roman soldiers, and the return of Rona Munro to “Doctor Who” after nearly thirty years—that’s what we have in “The Eaters of Light.” Jason and David appreciate the sparkling dialogue, while trying to ignore some of the plot mechanics. And finally, we spend some time talking about Missy’s story arc and the best role of The Master in a modern version of “Doctor Who.” Host Jason Snell with David J. Loehr.