I'm bothering to post this information because people I know in real life who read this blog have asked me when it'll be back. Now you know. The BBC's Media Centre has this synopsis:
"The Doctor’s search for Clara Oswald brings him to modern day London, where wifi is everywhere.Ironically, given the spoilers for the episode already in the air, the first result on Google for the phrase "wi-fi soup", are the good people at Urban Spoon, as though the minutes of the show's tone meeting have gained sentience and are now threatening our reality.
"Humanity lives in a wi-fi soup. But something dangerous is lurking in the signals, picking off minds and imprisoning them. As Clara becomes the target of this insidious menace, the Doctor races to save her and the world from an ancient enemy."