Someone patiently painted on thirteen doors of an apartment building in Paris, a large black number four, upside down, with a wide base. Something that makes Inspector Adamsberg wonder hesitantly, whether it is a threat or just a painting.
On the other side of the French capital, Josh, an unemployed sailor from Brittany, a former convict, daily shouts news and paid advertisements in Montparnasse, acting as a broker. But lately, some of them seem completely incomprehensible to him, while his grandfather whispers persistently in his ear at night: "Be careful, Josh. Only good thoughts do not pass through a person's mind!"