Once upon a time, in the 16th century, Hernan Cortes, who conquered the Aztecs, took possession of the sacred necklace of Montezuma - unsurpassed in beauty and possessing magical properties. The news that the emerald jewelry was safe and sound and was in France was accompanied by a series of terrible and unpredictable events: the disappearance of the famous Parisian antique dealer Gilles Vaubrun on the eve of his wedding to a young Mexican aristocrat, the death of his butler, threats against the family of Prince Morosini. In three months, Aldo Morosini, a close friend of the missing groom and a brilliant connoisseur of legendary jewelry, must find the jewelry - the most valuable of all existing in the world, the fate of which has not been known to anyone for four centuries...