The director of the French Ministry of the Interior summons Serge Cazals, an Interpol agent, to unmask the leaders of an organization that sells military intelligence and has just made a name for itself with the assassination of Secret Service ace Georges Dandieu. Cazals is soon spotted by his adversaries and dangerously threatened. Through an intermediary in the organization, he obtains a telephone number that leads him to various leads, but to no avail. He then decides to set a trap, with the help of his friend Violaine.

A la fin de la deuxième guerre mondiale, alors que les grandes puissances mettent sur pied des entreprises d'espionnage et de contre-espionnage très puissantes, un agent des services secrets français tire au clair une ténébreuse affaire de documents qui met en jeu la sécurité internationale.