Paris, at the beginning of the 20th century. The "Belle Époque" is flourishing - but so is crime. The number of crimes in the French capital increases rapidly and when the fight against them seems hopeless, the head of the government creates a new special police unit: the so-called "mobile brigades". Equipped with the latest technology, the best sniffer dogs and the newest automobiles, these brigades hunt down the city's criminals! The first episode of the cult series around Jean-Claude Bouillon as Inspector Paul Valentin.