London, 1907: When the Season's most accomplished and elegant debutante, Victoria Goldsborough, collapses and dies at her engagement ball, the great and good of London Society prepare to mourn the tragic loss of an upstanding young woman. But all is not what it seems, and after a toxic beverage is revealed to be the cause of death, the king himself instructs Lady Emily and her husband Colin Hargreaves to unearth the truth.

Who would want to harm one of the most popular women of the year? Is it her fiancé with whom she had an unusually brief courtship; a rival for his affections bitter at being cast aside; her best friend who is almost certainly hiding a secret from Colin and Emily; a disappointed suitor with a hidden gambling habit; or a notorious jewel thief who has taken a priceless tiara from the Goldsborough home? When a second debutante succumbs to poison, the race is on to find a ruthless killer.

Emily and Colin's investigation leads to a centuries old tomb in the center of London with a mysterious link to another death dating back to Roman times and the violent reign of Boudica, ancient Britain's fearsome warrior queen. As the stakes rise and the clock ticks down, Emily must find the killer before they strike again.