A French nobleman is enlisted by a wealthy widow to retrieve a priceless emerald stolen from her collection. He is aided in his quest by a Dutch spy posing as a noblewoman, but the duo have to contend with the cunning villain who stole the gem and has the support of the French king. Swashbuckling adventure, with Cornel Wilde, Jean Wallace and Herbert Lom.

Squire Pierre St. Laurent returns from wars in India to 17th-century provincial France to find his estate confiscated by governor Narbonne, for back taxes, and resold to Katrina, a Dutch Countess. Katrina offers to return Pierre's property if he will help her get possession of the 'Star of India,' a fabulous sapphire, held at the moment by Narbonne.