In Cannes, Arsène Lupin, posing as a policeman, finds himself entrusted by Guerchard with overseeing an exhibition of solid gold statues. Kesselbach, one of the exhibitors, boasts of possessing an absolutely inviolable safe. But Lupin knows that the man murdered Professor Ramirez in order to retain sole possession of the Inca treasure. In his normal guise, Lupin pays Kesselbach a visit.