Peter Hunkeler, now a retired inspector of the Basel police force, hospitalized following surgery and shared the room with an old acquaintance: Stephan Fankhauser, a colourful character. Once a wild member of the 1968 student movement, over the course of the years he made his way through the institutions and became director of a bank. Now Fankhauser is seriously ill. One night, Hunkeler had just been given a sleeping pill, he noticed a nurse with a ruby ring on her hand administering an injection to the fellow patient. Strangely, Fankhauser is resisting it intently. And does not the night nurse usually wear a diamond ring? The next morning, when Hunkeler wakes up, Fankhauser is dead. Was it all just a dream? Hunkeler is not sure, but he resolves to get to the bottom of the matter.