S1·E53 Maigret and the Seven Little Crosses

Mid-August in Paris, and Maigret is due to leave on vacation. His travel plans get interrupted when a 60-year-old woman is killed in her own apartment. The police suspect it may be the latest murder committed by a serial killer. The same night, anonymous calls for police assistance come in from all over Paris, as if someone's trying to send a cryptic message.