Blake Hansford, second son of the Duke of Warwick is widely known as one of London's notoriously popular rakes. Unbeknownst to the family, however, save the duke himself, his son Blake-code name Eagle-is actually a secret agent for the Home Office, and a liaison with the Bow Street Runners. When a family friend is found to have committed suicide, the Duke is suspicious and enlists Blake's help in investigating what transpired. Blake quickly recognizes there are too many inconsistencies surrounding his manner of death and concludes the suicide was staged to cover up something far more sinister. Emily Johnston, still reeling from the shock and despair of her father's suicide, is convinced he must have left some type of farewell letter to her with a reason for his bewildering actions. She decides it must be hidden in his desk in the secret compartment they frequently used when she was a child to share lighthearted confidences. When Emily slips back into the house to search for what she hopes is a message from her father, she is stunned to find the desk has vanished and she is not the only one with an interest in its whereabouts as she interrupts Blake along with a band of thieves all intent on finding the missing fixture...and what may be inside it. Blake's confrontation with the thugs convinces him that he is dealing with someone prepared to destroy anybody standing in his way and knows he must do whatever he can to keep Emily safe from harm. But how does an apparent happy-go-lucky womanizer justify his actions while executing an investigation into an obvious murder without revealing his true purpose? Blake has no other choice but to enlist Emily's help. Together they search for answers only to find themselves scrambling one step behind a cunning individual clearly willing to do anything, even kill, to keep his secret hidden.