Other People's Money by Emile Gaboriau

The commissaries of police of Paris, as a general thing, are no simpletons; and, if they are ever taken in, it is because it has suited them to be taken in.

Their modest title covers the most important, perhaps, of magistracies, almost the only one known to the lower classes; an enormous power, and an influence so decisive, that the most sensible statesman of the reign of Louis Philippe ventured once to say, "Give me twenty good commissaries of police in Paris, and I'll undertake to suppress any government: net profit, one hundred millions."