The Cockatrice Boys

"What does a cockatrice enjoy most for dinner? Anyone it can find." So the alarmed inhabitants of England discover when a plague of monsters--known as cockatrices--invade their country and begin gobbling them up. They must be stopped! A plucky band of survivors dubbed the Cockatrice Corps--including youngsters Dakin and Sauna--decide to fight back. But how? A rollicking adventure filled with breathtaking twists and turns, The Cockatrice Boys is Joan Aiken at her comic best.
But there is also a powerful message in her only full length Sci- Fi (or even Cli-Fi!) YA novel as Joan Aiken imagines the result of human folly, in an earlier version of global warming, with the hole created in the ozone layer becoming a channel for evil to arrive on earth as an invasion of monstrous creatures. Joan Aiken believed in the power of the imagination, and using stories to prepare us for our future.
In The Cockatrice Boys she wrote:"People need stories...to remind them that reality is not only what we can see or smell or touch. Reality is in as many layers as the globe we live on itself, going inwards to a central core of red-hot mystery, and outwards to unguessable space. People's minds need detaching, every now and then, from the plain necessities of daily life. People need to be reminded of these other dimensions above us and below us.
Stories do that." "Besides being a daringly original, funny, scary, and morally instructive book, it also contains one of the strongest statements of the purpose of fantasy stories and fairy tales .