Roderigo — the natural son of the great Count d’ Olivarez, minister to Philip IV of Spain — was, upon his father’s disgrace, given over when very young to the care of a certain Don Ambrosio, and by him brought up as his own child. Ambrosio has one son, Marcel, and two daughters, Hippolita and Cleonte. Marcel, whilst in Flanders, promised Hippolita to his friend Alonzo. This Alonzo is the son of a lady Octavia and Don Manuel. But Manuel’s rival in Octavia’s love, Alonzo, stole their boy when an infant and brought him up to arms, giving him his own name. Pedro, an old servant, who is cognizant of this, is sworn to secrecy. Alonzo arrives in Madrid purposing to wed Hippolita as he desires to ally himself with so ancient and powerful a family as Ambrosio’s. Hippolita, however, having been betrayed by a German named Antonio, has fled, and now resides in a house of pleasure in the town, having assumed the habit of a Venetian courtezan. Alonzo meeting Euphemia, sister to his friend Lovis, becomes enamoured of her, and the lady grants him a rendezvous at a house where they will be uninterrupted — it happens this house is the bagnio where Hippolita is secreted. Marcel, on his way to visit Clarinda, whom he loves, recognizes Alonzo and follows him to his rendezvous, Olinda, Euphemia’s maid, mistakenly introduces Marcel to her mistress. Euphemia is veiled and Marcel, who has heard that his sister is living in that house, in his turn mistakes the lady for Hippolita, more especially as he meets Antonio there. The two men fight, but Alonzo entering interferes. Antonio escapes, bearing away Hippolita. Euphemia, whom Marcel in a passion of revenge would kill, is soon discovered not to be Hippolita, and the angry brother duly retires from the scene. Alonzo, however, leaving the house is accosted for Marcel by Dormida, Clarinda’s maid, who gives him the key to their house. Alonzo enters followed by Marcel who is close on his heels. They jostle and fight in the darkness of the hall within, and Alonzo departs leaving Marcel wounded. Dormida fearing trouble drags Clarinda forth and meeting Alonzo in the street they throw themselves on his honourable protection. A complete stranger, in his dilemma he escorts them to the mansion of Ambrosio, and they chance on Cleonte’s chamber. She has just had a visit from Silvio (under which name Roderigo passes), who is burning with passion for her but shrinks from his supposed sister. Cleonte offers the two ladies a refuge and Alonzo retires. With the aid of his friend Lovis he assumes the habit of Haunce van Ezel, a Dutch boor who is contracted to Euphemia, and, as Haunce, courts Lovis’ sister with the full approbation of their father Don Carlo. When Haunce himself appears he is greeted with some familiarity as having been at the house before. The Dutch Lover, who has newly arrived, chances on a strife between Antonio and Hippolita and interfering disarms Antonio, wounding him in the face. Cleonte meantime has introduced her guest Clarinda to Silvio, and Marcel seeing them together concludes that his own brother is the man who fought him on the previous night and indeed his favoured rival. At once he challenges him and they arrange to have a duel in a grove near the town. Here, however, comes Hippolita disguised in man’s attire, awaiting Antonio to whom she has sent a billet signed ‘Alonzo’. She retires, whilst Silvio appears, and when he is engaged with Marcel, Alonzo rushes in and parts them. Alonzo avows that it was he who caused the confusion with Clarinda, and arranges to meet Marcel later in another spot. Antonio next arrives and Hippolita, calling herself Alonzo, draws, but Alonzo himself insists on taking up the quarrel. At the clash of steel Marcel returns and all four fight, Marcel with Hippolita, whom he wounds, Alonzo with Antonio, whom he disarms — Hippolita reveals herself, Alonzo claims her, but Antonio declaring that he is bound to her by sacred vows rescues her from Marcel’s vengeance and obtains his forgiveness. All return to Ambrosio’s house where they find Cleonte and Clarinda. Explanations ensue, and Marcel is at Clarinda’s feet. Pedro, however, who attends Alonzo, recognizes his old fellow-servant, Dormida, duenna to Clarinda, and learning Don Manuel is dead, reveals that Alonzo is Clarinda’s brother, also handing over papers left by Don Alonzo the foster-father, which bestow 12,000 crowns a year on his adopted son, Alonzo portions Clarinda and gives her to Marcel. Francisca, woman to Cleonte, informs Silvio that Cleonte will yield to him — Silvio, suddenly revolted, declares he will present himself, but secretly resolves to poinard his sister. Marcel who has overheard the conference, beside himself with rage, dashes on Silvio with dagger drawn and when checked by Ambrosio and the rest who rush in at Francisca’s cries makes known the cause of his wrath. Francisca confesses that Cleonte had sent no such message, but herself purposed to take her mistress’ place that night and receive Silvio. Ambrosio then reveals the secret of Silvio’s birth and gives Cleonte to him, in his joy even taking Hippolita to his arms since Antonio has married her. Alonzo, meanwhile, disguised as Haunce has been united to Euphemia. He is discovered by the arrival on the scene of the real Haunce accompanied by Gload, a foolish tutor. Carlo is soon reconciled to the new bridegroom, whilst Haunce and Gload joining in a masquerade find themselves unexpectedly wedded to Olinda and Dorice, two women attendant on the lady Euphemia.