Eugène François Vidocq was born in 1775 in Arras, the son of a prosperous baker, and was in trouble almost at once. At 13 he pawned the family silver, and the two weeks in jail his father arranged as a lesson served mostly as an introduction to the underworld. He robbed the bakery cash box, played a raw meat eating cannibal in a traveling carnival, fought at Valmy, dueled his own officers, deserted repeatedly, and posed as a Hussar captain in a roving band of con men. A forgery charge sent him to the galleys at Brest, and a decade of escapes and recaptures followed.

In 1809, aged 34 and blackmailed by people who knew his real identity, he offered himself to the Paris police as an informant. This episode traces what came next: 21 months spying from a cell in La Force, a staged prison break to protect his cover, and the founding in 1811 of the Brigade de la Sûreté, a plainclothes unit staffed with ex-convicts. Along the way he built the tools of modern detection, drew the contempt of aristocratic police chiefs, and gave novelists a character they could not resist.

• He once escaped a prison hospital disguised in a stolen nun’s habit, and learned the street fighting style savate while locked up.
• Instead of brutal interrogations, he invited suspects to dinner, poured wine, and talked his way to confessions and new informants.
• His index card system recorded aliases, convictions, handwriting, and methods, and he was the first to make plaster casts of shoe prints, while his chemists developed tamper-proof paper and indelible ink.
• In an 1822 case he had the bullet removed from a murdered wife’s head and showed it was too large for her husband’s dueling pistols, then matched it to her lover’s gun.
• In 1833 he opened the first known private detective agency. He died in 1857 at 81, having inspired Poe’s Dupin and both Jean Valjean and Javert in Les Miserables.