"Karl-Dieter, avenge us!" demand Agathe, Bertha, and Cecilie from their friend in a dream. "Save us, they must have called out," comments his partner, Commissioner Mütze, with a calm demeanor. But when Karl-Dieter lovingly prepares the drowned friends for their funeral on Spiekeroog, he makes a horrifying discovery. And now Mütze must also admit that this is not a natural death. Together with the island policeman Ahsen, he embarks once again on a hunt for the murderer. In the meantime, Karl-Dieter is supposed to focus entirely on preparing the burial ceremony. So much for the theory... Because Karl-Dieter discovers not only that the old friends had stumbled upon a crime of international proportions, but they were also on the verge of uncovering perhaps the island's best-kept secret.