Marguerite de Valois, the beautiful Queen of Navarre, who is anxious to reconcile the bitterly hostile parties of Catholics and Huguenots, persuades the Comte de Saint Bris, a prominent Catholic, to allow his daughter Valentine to marry Raoul de Nangis, a young Huguenot noble.  Valentine is already betrothed to the gallant and amorous Comte de Nevers, but she pays him a nocturnal visit in his own palace, and induces him to release her from her engagement.  During her interview with Nevers she is perceived by Raoul, and recognised as a lady whom he lately rescued from insult and has loved passionately ever since.  In his eyes there is only one possible construction to be put upon her presence in Nevers’ palace, and he hastens to dismiss her from his mind.  Immediately upon his decision comes a message from the Queen bidding him hasten to her palace in Touraine upon important affairs of state.  When he arrives she unfolds her plan, and he, knowing Valentine only by sight, not by name, gladly consents.  When, in the presence of the assembled nobles, he recognises in his destined bride the presumed mistress of Nevers, he casts her from him, and vows to prefer death to such intolerable disgrace.

The scene of the next act is in the Pre aux Clercs, in the outskirts of Paris.  Valentine, who is to be married that night to Nevers, obtains leave to pass some hours in prayer in a chapel.  While she is there she overhears the details of a plot devised by Saint Bris for the assassination of Raoul, in order to avenge the affront put upon himself and his daughter.  Valentine contrives to warn Marcel, Raoul’s old servant, of this, and he assembles his Huguenot comrades hard by, who rush in at the first clash of steel and join the combat.  The fight is interrupted by the entrance of the Queen.  When she finds out who are the principal combatants, she reproves them sharply and tells Raoul the real story of Valentine’s visit to Nevers.  The act ends with the marriage festivities, while Raoul is torn by an agony of love and remorse.

In the next act Raoul contrives to gain admittance to Nevers’ house, and there has an interview with Valentine.  They are interrupted by the entrance of Saint Bris and his followers, whereupon Valentine conceals Raoul behind the arras.  From his place of concealment he hears Saint Bris unfold the plan of the massacre of Saint Bartholomew, which is to be carried out that night.  The conspirators swear a solemn oath to exterminate the Huguenots, and their daggers are consecrated by attendant priests.  Nevers alone refuses to take part in the butchery.  When they all have left, Raoul comes out of his hiding-place, and in spite of the prayers and protestations of Valentine, leaps from the window at the sound of the fatal tocsin, and hastens to join his friends.  In the last act, which is rarely performed in England, Raoul first warns Henry of Navarre and the Huguenot nobles, assembled at the Hotel de Sens, of the massacre, and then joins the melee in the streets.  Valentine has followed him, and after vainly endeavouring to make him don the white scarf which is worn that night by all Catholics, she throws in her lot with his, and dies in his arms, after they have been solemnly joined in wedlock by the wounded and dying Marcel.