In retrospect, the clues were always there – that remarkable central sequence of Cloud Atlas narrated entirely in an invented future tongue; the moment when The Bone Clocks mutates from the story of a lovelorn adolescent girl into something nightmarishly strange – but the truth is now undeniable. With the publication of his seventh novel, Slade House, David Mitchell has outed himself as a full-on science-fiction writer – or, at the very least, as a frequent and enthusiastic practitioner of the form. Certainly, had this book been written by another, less-feted hand, by someone who hadn’t been nominated for the Man Booker Prize or, in 2003, made the cut of Granta’s finest, it might have been placed without compunction in those aisles of bookshops that are labelled ‘SF’, ‘fantasy’ and ‘horror’.

The plot of Slade House is simple. It tells the