The worlds of sci-fi and horror collide in the bleak-as-night, technology-fuelled anthology series Black Mirror. Each episode takes on a different nightmarish idea, from the choose-your-own-adventure madness of "Bandersnatch" to the all-too-real computer role-playing game in "USS Callister." The one thing every episode has in common is that they will all leave you deeply suspicious of your smart phone.