Suspecting that a traitor is delivering vital state information to the French, King Charles and his brother James devise a plan to intercept the messages and catch the traitor. Justin de Beaufort the Duke of Lancaster takes on the guise of a highway man in order to stop coaches on their way to and from London in the hope of finding the information that will uncover the traitor. The dashing and handsome highway man steals papers and packages along with many a maiden's heart. Until one fateful evening he stops a coach with Dominique de Sevigne as the only occupant. As Dominique realises that she is falling in love with the Duke of Lancaster, she knows that she must not succumb to her feelings until she has cleared her dead father's name of the charge of treason. When Dominique suddenly leaves England for France Justin is convinced that she is the traitor he seeks and follows her to the French Court of King Louis where the intrigue deepens.