A former convict is murdered because he recognized an escaped convict in an army colonel. Vidocq infiltrates the colonel's organization. He deals with burglars, but also spies: goods stolen in Paris are sold in London and vice versa... but more often than not, confidential papers are stolen. An embassy secretary wants to forbid Vidocq to deal with the case. He is the head of the network. As for the so-called colonel, he has been replaced by the real colonel, who has gone mad, at the Toulon prison. Vidocq will try to make the opposite substitution...