"Blaise Vanadric changed you into a sword," he said finally, "because you would not change for him."

Paradoxically, Mr Alfredson has managed to keep the book's slow, cerebral mood while at the same time speeding up the narrative about agents and double agents.

That was until a village playwright called Valerie Chidson decided to research Emma's disappearance for a short fictionalised film after seeing a picture of the teenager in an old village photograph.