Steven Moffat revealed that the episode originated with the decision, "I'm going to do a chamber piece, with no money, in the middle [of the eighth series], because I haven't done one in ages and I'd like to prove that I can actually write."
Steven Moffat discussed the episode in an interview, saying: "my impulse starting in that was just the idea, 'What does he do when he's got nothing [to] do?' Because he'd throw himself off a building if he thought it'd be interesting on the way down ... he's fascinated by anything. And here he's with nothing to do, so he just goes out poking things with a stick until something bites it. And I think that's quite interesting, isn't it? Sort of, there's a thrill seeker aspect."
In a 2007 short story, Corner of the Eye, Steven Moffat had already dealt with the idea of monsters who had the super-ability to hide (called Floofs). Previously, he had revived concepts from his short story What I Did on My Christmas Holidays by Sally Sparrow into his televised Blink.