I bought my daughter a Sherlock t-shirt for her birthday: “I don’t understand,” it says on the front and, on the back, “I still don’t understand”. The quotes are attributed to John Watson but they could apply to quite a lot of us, I imagine. We love to puzzle over the show, on Twitter or elsewhere, speculating as to twists in the plot (or in the characters). Watching is different to reading. There’s a social aspect to it, for one thing. We all watch the same episodes at the same time and we’re all waiting a week for What Comes Next; plenty of time for theories to abound.