Clockwork Angel (The Infernal Devices #1)

The year is 1878. Tessa Gray descends into London’s dark supernatural underworld in search of her missing brother. She soon discovers that her only allies are the demon-slaying Shadowhunters—including Will and Jem, the mysterious boys she is attracted to. Soon they find themselves up against the Pandemonium Club, a secret organization of vampires, demons, warlocks, and humans. Equipped with a magical army of unstoppable clockwork creatures, the Club is out to rule the British Empire, and only Tessa and her allies can stop them....