Late one night, in 1800, beleaguered Channel Island fishermen Gilliat and Willie, who have been forced into a life of smuggling because of the raging Napoleonic Wars, are startled when a beautiful woman rows to their Guernsey cove and asks for Lethierry, a local aristocrat. Gilliat insists on escorting the woman to Lethierry's home, unaware that she is an English spy named Drouette. After Drouette and Lethierry discuss details of her mission--to impersonate the Countess de Remuset, now imprisoned in London, and obtain information about the French Navy--Drouette goes to an inn to find Rantaine, Gilliat's business rival, who is to take her to France. Gilliat and Willie are also at the inn and before Drouette can leave with Rantaine, Gilliat brawls with him. After Gilliat knocks Rantaine unconscious, Drouette pays Gilliat to take her to France. Later, at sea, Willie and Gilliat suddenly change course, prompting Drouette to "confess" that she is rescuing her brother from a French prison. Touched by Drouette's story, Gilliat steers his boat back toward France and, upon landing, returns her money. Drouette then appears at the countess' chateau and meets her contact, the butler Ragan. Ragan informs Drouette, who greatly resembles the real countess, that she is to meet with General Latour, the head of the French spy network, as well as Fouche, the crafty chief of police. The next day, as Drouette is touring a hospital with the general, Gilliat spots her and learns that she is the countess. Aware of Latour's position, Gilliat assumes the worst and, just before sailing home with Willie and a cargo of brandy, sneaks into the chateau and abducts Drouette. As they sail toward Guernsey, Gilliat yells at the spy for tricking him and refuses to listen to her explanations. After Gilliat delivers Drouette to Lethierry, Lethierry secretly arranges with Rantaine to ship Drouette, who is due to meet Napoleon the following evening, back to France. Gilliat, meanwhile, begins to feel sorry for Drouette, who he assumes will be hanged, but then sees her departing in Rantaine's boat and swims after it. Gilliat boards and fights Rantaine and his mate, Blasquito, who finally knocks Gilliat out. When Rantaine announces he is going to kill Gilliat, Drouette intercedes, claiming there is a £1,000 reward for Gilliat's capture. Later, Drouette tries to convince the bound Gilliat of her innocence, but he still refuses to listen. Despite Gilliat's anger, Drouette professes her love and kisses him, then jumps overboard and swims to the chateau cove. The next day, Drouette meets Fouche, who has come to check security at the chateau in anticipation of Napoleon's visit. Drouette fools Fouche, until a servant mentions that the entire chateau staff was replaced shortly before the countess' return. Now suspicious, Fouche arranges with the countess' neighbor, Baron de Vaudrec, to dine with Drouette the following day and question her about her past. That evening, Drouette charms Napoleon and eavesdrops when he reveals to his officers his plans for the French fleet. Before Drouette can pass the information to Ragan, the baron arrives and determines that she is an imposter. Fouche locks Drouette up in the chateau dungeon and informs Napoleon, who demands the spy be killed. Ragan, however, has overheard Napoleon's conversation and sends a carrier pigeon message to Lethierre before being shot by Fouche. After receiving the message, Lethierre orders Gilliat, Willie and Rantaine, all of whom he has imprisoned on various charges, to rescue her and sends a coded carrier pigeon reply to Ragan. Lethierre's message, which details Drouette's escape, is intercepted by Fouche, but when he cannot decipher the code, he offers to spare Drouette's life if she unscrambles the message for him. Drouette gives Fouche false information, and Fouche pretends to be deceived, then has her followed when she sneaks away. Gilliat, meanwhile, has disembarked and is questioning his French brandy supplier about Ragan when Rantaine, who has decided to sell information to the French, confronts him at gunpoint. Rantaine ties up Gilliat, but Willie appears and shoots the traitor just as the pursued Drouette finds them. Gilliat and Willie manage to hold off Fouche and his soldiers long enough to escape with Drouette, and they all swim to Gilliat's waiting boat. Later, with their freedom assured, Gilliat and Drouette enjoy a passionate kiss.
