During his absence, secret (and normally undecipherable) documents have been stolen from Andrei Smoloff, a cultural attaché at the Soviet Embassy in Paris. Through an indiscretion, the French Secret Services are made aware of the affair and a team consisting of Captain Jean de Lursac and Vigo Currici is set up by the "Commander" to pursue the matter. Meanwhile Smoloff is summoned at the Soviet Embassy by Borghine, the chief of the Russian Secret Services in Paris. The victim of the theft has to struggle hard to prove his innocence. But is Smoloff really innocent as he claims or does he play a double game? And is France connected in any way with the events? It will be up to Jean and Vigo to find out.