Not such a revelation within the episode as much as much as what we learned about the show. The phrase 'hiding behind the sofa' has always been associated with the show, but how many times has it genuinely been scary? Deep Breath was creepy. The Silence were chilling. The Angels - well in Blink they terrified us - but we've really seen that phrase manifested in the show we're watching. But this week, Moffat did it, delivering his scariest moment since the Angels turned out the lights in Blink. The thing under the blanket was genuinely chilling and sure to give children nightmares. It only got considerably worse when it began to move, getting closer and closer behind Clara's back. Add to it a creepy score and lots of heavy breathing and Doctor Who delivered on the chills promised in the trailer. There was a lot of talk of Doctor Who being too scary after the Silence in appeared at the start of series six. They certainly were creepy but it was Listen that showed hiding behind the sofa isn't always a bad thing...