The Outlaw's Ransom (The Folville Chronicles)

When potter's daughter Mathilda is kidnapped by the notorious Folville brothers as punishment for her father's debts, she fears for her life. Although of noble birth, the Folvilles are infamous throughout the county for using crime to rule their lands--and for using any means necessary to deliver their distinctive brand of 'justice'.
Mathilda must prove her worth to the Folvilles in order to win her freedom.

To do so, she must go against her instincts and, disguised as the betrothed of Robert de Folville, undertake a mission that will send her to Bakewell in Derbyshire, and the home of Nicholas Coterel, one of the most villainous men in England.

With her life in the hands of more than one dangerous brigand, Mathilda must win the trust of the Folville's housekeeper, Sarah, and Robert Folville himself if she has any chance of survival.
Never have the teachings gleaned from the tales of Robyn Hode been so useful...