Colpo grosso... grossissimo... anzi probabile

Three clumsy thieves come up with a robbery scheme against the "Grandi Magazzini Romani". They call to their aid a skilled "only by reputation" French burglar, Pierre Le Compte. He arrives together with his lover Jacqueline. The girl has the opportunity to meet Sandro Menegatti, who, after an internship, will become president of the "Grandi Magazine" company. Sandro amazes Jacqueline in showing her his perfect knowledge of the "Department Stores" and the ease of accessing them. When asked, the young man - mostly to satisfy Jaqueline whom he is in love with - agrees to take part in the robbery. The plan succeeds, but the safe is empty: in fact Sandro has removed the money.