The threat of invasion by Napoleon hangs over Britain. Drouette, woman of mystery, meets Gilliatt, Guernsey smuggler, when he directs her to the house of Lethierry, Chief of Customs for the British Channel Islands. After injuring his rival, who has undertaken to escort Drouette back to her native France, Gilliatt reluctantly agrees to take over the mission. Drouette is ostensibly returning home to ransom her brother, held by the French revolutionaries. Later, Gilliatt is told she is the Countess de Remuset, a French espionage agent!