It's 1902, you're stuck for somewhere to spend your leave from the Foreign Office, and then you get a telegram inviting you to go duck-shooting on a yacht in the Baltic. But, when you get there, there are no ducks, and the yacht only has room for two, and your friend wants you to help him untangle an international spying game of treason and riddling identity changes. You also have to learn to sail, fast, in the first gales of autumn. The German navy are interested in your activities, and someone is trying to prove that you're a spy. Which you are, inadvertently. It's all rather awkward, but it's becoming a mission of national importance. For readers who don't mind oil stains on board as long as there is fresh bread once a week.