Wartime Germany: Marie, a concentration camp escapee on the run from the Nazis, narrowly escapes drowing when she is rescued by Wolfe Kristan a half-mad lighthouse keeper. Brought aboard the lighthouse itself, she begins to fall in love with the assistant keeper who, unknown to her, is a British spy. As the couple become more intimate, Kristan's jealously finally pushes him over the brink and into full-blown madness.