Steven Moffat loves childhood fears. He’s mined them for some of nuWho’s most effective villains: Something lurking in the dark (the Vashta Nerada), a threat waiting to pounce the moment you look away (the Weeping Angels), and now, the monster under your bed. These creatures tap into the intense, pervasive fears so many experience as children and like its predecessors, “Listen” is hugely successful drawing from this well. It also takes a common and, when explored, curious habit and exploits it for significant dramatic potential: why do people talk to themselves when no one’s around? Both ideas have been explored by Moffat to some extent already (“The Girl in the Fireplace”, the Silence), and so here he puts them together, hoping that between the two, there’s enough new material to make the story work.