Natalina is in hospital because of heart problems. While Don Matteo visits her, a strange incident occurs: A doctor falls from the fourth floor of the hospital. It looks like suicide but Don Matteo has heard the man's last words: unconnected syllables lacking in sense. To break the silence that seems to engulf the hospital, Anceschi decides to smuggle Cecchini in as a nurse. With the help of Don Matteo, they discover strange drugs and medication as well as some mysterious deaths.