One morning an agitated man calls the Police judiciaire asking for Maigret. He claims he's being followed by someone trying to kill him. Before Maigret can get the details he hangs up, calls back again from various cafés until the calls finally stop. That night his body is found, his face badly beaten and has been stabbed to death. Riddled with guilt for not having saved "his" dead man, Maigret is determined to find the murderer.