Leona Hewitt retrieves a stolen family relic, a powerful crystal, from Lord Delbridge's private museum and encounters mesmerist Thaddeus Ware, whose powers do not work on her as he would wish, and the two try to evade a killer called the Midnight Monster.

Elizabeth Ashburton, hiding in a carriage to avoid being seen by an obsessed suitor, learns to her dismay that the vehicle belongs to the notorious Rowland Manning, who virtually holds her prisoner at his estate until he feels she has paid off her debt to him, giving them time to fall in love with each other.