A thrilling Second World War saga - In the summer of 1936, a teenage German boy, Reinhard Richter, is sailing in his father’s yacht, Sturmwind, off Scotland. Moored in an island cove, he meets Stroma Mackay and is captivated by her. He persuades her to write to him in Hamburg, and their correspondence continues until war is declared. Reinhard joins the elite U-boat service, while Stroma serves as a plotter in the WRNS, helping fight the desperate battle against marauding U-boats - the wolf packs. It seems impossible that they will ever meet again.