Content Warning: This section discusses racist and racially insensitive attitudes and language and contains references to suicide, drug and alcohol addiction, and mental health conditions; depictions of the aftermath of two deaths by suicide; and descriptions of corpses and murders. 

Renowned Parisian detective Aristide Valentin searches for a criminal named Hercule Flambeau, who has used his uncommon size and strength to commit several recent robberies. Valentin has tracked him to a dairy company in London, where Flambeau sells milk cans. Taking a train from Essex to London, he meets a short priest who is carrying an umbrella and multiple paper parcels. The priest tells Valentin—loudly enough for anyone to hear—that he must take great care with these parcels because inside one of them is a valuable silver item inlaid with blue stones. Before the priest leaves the train at Tottenham, Valentin warns him not to tell people about the valuable object that he is carrying if he doesn’t want it stolen. When the train arrives in London, Valentin continues his search for Flambeau while admiring the city’s scenery. While he is an intelligent and straightforward man, he likes to look in the wrong places during an investigation, believing that the best way to learn the criminal’s thinking is by anticipating the criminal’s potential thought patterns.