The Clockwork Fairy Kingdom Trilogy

Adele - the beautiful fairy queen with wings of clockwork - despairs when her husband, the master tinker, dies before he finishes the great machine that will reignite the human-fairy war and drive the humans away. When she meets Dale, a human boy with natural talent - who can finish the machine - she enslaves him and binds his will with her fairy magic. However, Dale's twin sister, Nora, who has only recently discovered that she is a maker and has power of her own, escapes before she can be taken as well.

Five years have passed. The worlds above and below have recovered and changed. The fairies from the Clockwork Kingdom return every year, asking for Dale's help in vain. This year Cornelius, the head of the fairies, brings dread news: Kostya has returned. The maker has taught herself what she could about magic, but no teacher has ever arrived. Finally a herald manages to break through the spells surrounding the town to warn Nora that something, perhaps a monster, has been keeping them at bay. And it is stalking her for her power and her life.