Following the end of the Great European War, as described in "Gray Tide In The East", it is now 1923. The Americans, and the British, although not involved in the war, are both nervous about the continuing expansion of Germany's power, influence and military capabilities.In particular, what are the Germans doing on the former French colony of Martinique? Surely they would not dare to build a major naval base there, so close to the coast of the United States? That would be intolerable, and would risk war with the USA. The U.S. State Department needs to know what is really happening and, before anything else, U.S. Naval Intelligence must conduct some discrete surveillance of the island...** This short book is the first part of "Tidal Effects", which is the second full book in the series that started with "Gray Tide in the East" and which contains both this book and "Rip-Tide". This book is a complete story in itself, and includes illustrations from historical archives.