Für Mord kein Beweis: After a fierce argument Steffi Zinn′s husband leaves the joint flat and stays away from home over night. The next morning, his wife Steffi has disappeared and is reported as a missing person. Captain Lohm takes over the case and at first looks for signs of a murder, but to no avail. Then, Steffi′s body is found in a lake. After her funeral, a stranger who had attended Steffi′s funeral for a short time is also found dead in a lake, and the connection between the two cases becomes apparent.