Dedicated to the memory of the Young Adult writers whose work I used to devour when I was young: Capt. W. E. Johns, Hugh Walters, Andre Norton, Malcolm Saville, Alan E. Norse and John Christopher; and also to the friendship and support of those members of the latest generation that I’m fortunate enough to know: Ben Jeapes, Stephen Cole, Justin Richards, Gus Smith and the incomparable Charlie Higson.

And with grateful acknowledgements to:

Rebecca McNally and Robert Kirby, for having faith; Jon Lellenberg, Charles Foley and Andrea Plunkett, for giving permission; Gareth Pugh, for telling me all about bees; and Nigel McCreary, for keeping me sane on the journey.

The first time Matthew Arnatt saw the cloud of death, it was floating out of the first-floor window of a house near where he was living.

He was scurrying along the High Street in the market town of Farnham, looking for any fruit or crusts of bread that a careless passer-by might have dropped. His eyes should have been scanning the ground, but he kept looking up at the houses and the shops and at the thronging people all around him. He was only fourteen, and as far as he could remember he’d never been in a town this large before. In this, the prosperous part of Farnham, the older wood-beamed buildings leaned over into the street, with their upper rooms looming like solid clouds above anybody underneath.

The road was cobbled with smooth, fist-sized stones for part of its length, but some distance ahead the cobbles gave way to packed earth from which clouds of dust rose up as the horses and the carts clattered past. Every few yards sat a pile of horse manure: some fresh and steaming, surrounded by flies; some dry and old, like strands of hay or grass that had been clumped together and somehow stuck.