1312. Sir Hugh Corbett, Keeper of the Secret Seal, has returned from the West Country to find Westminster in chaos. Edward II has fled in an attempt to protect his favourite from the wrath of his noblemen; and a royal clerk has been found dead, poisoned in a locked chamber.

Drawn into a maze of murder both at Westminster and at the Convent of Saint Sulpice, where young novices have started to disappear, Corbett quickly establishes a connection between the two mysteries. As other killings follow, Corbett's investigation leads him to a high-class brothel and its sinister owner, Mother Midnight. Challenged to a duel and hunted by a guild of ruthless assassins, Corbett and his loyal henchmen, Ranulf and Chanson, face a sea of troubles.

And Corbett must call upon his wit and ingenuity to halt the tide of disaster that threatens to engulf him...