After five years of tracking and capturing spies on English soil, Philip Jonquil, Earl of Lampton, is in pursuit of his last quarry. But at a traveler's inn, he encounters an unexpected and far more maddening foe: Sorrel Kendrick, a young lady who is strikingly pretty, shockingly outspoken, and entirely unimpressed with him. Indeed, Sorrel cannot believe the nerve of this gentleman, who rudely accuses her of theft and insults her feminine dignity. Doubly annoyed when they both end up at a party hosted by mutual friends, Philip and Sorrel privately declare war on one another. But Philip's tactics, which range from flirting to indifference, soon backfire as he finds himself reluctantly enjoying Sorrel's company; and, much to her dismay, Sorrel finds Philip's odd manner to be increasingly endearing. In the midst of this waning war and growing attraction, Philip catches wind of the French spy he's been tracking, and Sorrel inadvertently stumbles upon a crucial piece of the puzzle, making her indispensable to the mission. But can two proud hearts negotiate a ceasefire when cooperation matters most?