In a tale steeped in action, romance, and the gaslit intrigue of Victorian London, Mary Quinn's detective skills are pitted against a cunning and desperate opponent. Mary Quinn has a lot on her mind. James Easton, her longtime love interest, wants to marry her; but despite her feelings, independent-minded Mary hesitates. Meanwhile, the Agency has asked Mary to take on a dangerous case: convicted fraudster Henry Thorold is dying in prison, and Mary must watch for the return of his estranged wife, an accomplished criminal herself who has a potentially deadly grudge against James. Finally, a Chinese prizefighter has arrived in town, and Mary can't shake a feeling that he is somehow familiar. With the stakes higher than ever, can Mary balance family secrets, conflicting loyalties, and professional expertise to bring a criminal to justice and find her own happiness?