Trey Harrow, the Earl of Chelmsworth, has never been so furious in his life. When his oldest and closest friend, Jack Cavanaugh, the Duke of Brighton, mistakenly seduces Trey's sister, the earl vows revenge.

As the Duke and Duchess of Brighton are leaving their wedding, Trey puts his plan into action by kidnapping Jack's own sister. He sends an ominous missive that simply says, "your sister for mine."

Lady Lucinda Cavanaugh is terrified as she is thrown blindfolded into a carriage and raced away from her family and friends. When she discovers who her kidnapper is, she is at least assured she will not be physically harmed. But Lucy is also furious that Trey would risk destroying her reputation just to get back at Jack.

Can Lucy convince Trey that Jack and Sophie are in love, so he will return her before her situation gets out and she is ruined? Or will Trey find himself with more in the same circumstances as Jack?