When mechanical genius Emily is kidnapped by rogue automatons, Finley Jayne and her fellow misfits fear the worst. What's left of their archenemy, The Machinist, hungers to be resurrected, and Emily must transplant his consciousness into one of his automatons—or forfeit her friends' lives.

With Griffin being mysteriously tormented by the Aether, the young duke's sanity is close to the breaking point. Seeking help, Finley turns to Jack Dandy, but trusting the master criminal is as dangerous as controlling her dark side. When Jack kisses her, Finley must finally confront her true feelings for him…and for Griffin.

Meanwhile, Sam is searching everywhere for Emily, from Whitechapel's desolate alleyways to Mayfair's elegant mansions. He would walk into hell for her, but the choice she must make will test them more than they could imagine.

To save those she cares about, Emily must confront The Machinist's ultimate creation—an automaton more human than machine. And if she's to have any chance of triumph, she must summon a strength even she doesn't know she has….