From the ground, flying is a wonderfully loose metaphor — for freedom and speed and ambition, for superhuman ease and laborless achievement. But Fran Wilde's Bone Universe series makes flying a fatal and real technical science. It isn't magic, but a controlled harnessing of something terrifyingly strong: the wind. The taut violence of flight — catching gusts, snapping wings, shaving the air — is the best and most real part of the novels. Not a broomstick whoosh or the effortless flutter of a superhero's cape, but groaning joints, deadly winds, an awful void below.