The scene is set on the grounds of the Castle of Formoutiers in France around the year 1200. The Count of Formoutiers has gone off to fight in the Crusades, followed by all of his noble vassals whose wives, daughters, and sisters have been left behind in the care of the Count’ s sister, the Countess Adèle. Having sworn a holy vow to remain chaste during the men’s absence, the women lead a life of virtuous solitude within the walls of the castle-which no man may enter.

Word has spread of the arrival of a saintly old hermit in the vicinity of the castle – a man whose advice is rumored to yield miraculous results. Ragonde, the Countess’ right-hand woman, joins a group of peasants who are waiting for the hermit to make an appearance. She has come to consult him about a cure for the terrible state of depression into which the beautiful young Countess has fallen. The old hermit agrees to lend his aid if the Countess will visit him in person. However…the “hermit” is in fact the disguised Count Ory, a well-known chaser of skirts who, with his companion Raimbaud, has devised this scheme as a means to gain access to the castle of Formoutiers, renowned for its many beautiful prisoners.

Meanwhile, the Tutor to Count Ory arrives on the scene with Isolier, the Count’s page, part of a search party organized to track down the garrulous young nobleman. Acting on a hunch concerning the true identity of the mysterious hermit, the Tutor leaves to inform his companions that their quarry is at hand. Isolier, unaware of any double identity, confides to the hermit that he is in love with the Countess Adèle. He reveals his daring plan – to disguise himself as a holy pilgrimess in order to be admitted inside the castle walls, where he will make an amorous declaration to his beloved.

The Countess consults the hermit. He frees her from her vow of chastity and recommends love as a remedy for her melancholy, but warns her to stay away from Isolier, faithful servant of the profligate Ory. The Tutor interrupts the interview and unmasks Ory, to the shock of all present. A messenger brings news of the imminent return of the Crusaders.

Secure within the castle walls, the Countess and her retinue reaffirm the moral superiority of their chaste stoicism, while outside a storm is brewing. A band of holy pilgrimesses begs for asylum from the tempest. The Countess consents, little suspecting that she is admitting the fox into the hen-house – for the pious guests are none other than Ory and his men. “Sister Clara” (Ory) thanks the Countess personally, with an ardor whose intensity seems to the Countess to be somewhat extreme.

Temporarily detoured from the pursuit of their primary goals by Raimbaud’s discovery of a well-stocked wine-cellar, the “pilgrimesses” are finally led off to their chambers. Isolier appears and reveals the true identity of the masqueraders, whose presence in the castle could prove particularly embarrassing-since the Crusaders have sent word that they will return this very night.

Ory slips into the Countess’ bedchamber to pay court to her. He does not realize that, deceived by the darkness, it is to his page Isolier that his increasingly amorous advances are directed. All masks are removed, however, when the trumpet fanfares of the approaching heroes are heard.

Honor is preserved with frantic split-second timing – the victorious defenders of the faith enter just as Ory and his companions are whisked out through a secret passageway by Isolier. The ladies can proudly confirm to their husbands and brothers that, during their absence, no man has been admitted into the castle of Formoutiers.