Though Mary has officially left the Agency, her former superiors have asked her 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, herself a notorious criminal with a potentially deadly grudge against James Easton, who wants to wed Mary. And Mary can't shake the feeling that a Chinese prizefighter newly arrived in town 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?