Act 4 opens with Belvile alone, imprisoned in a darkened room in Antonio’s house, bemoaning his ill fortune and the loss of his beloved Florinda. Antonio enters, wearing his nightclothes and holding a sword, despite his injured arm. He asks Belvile what he has done to earn Belvile’s hatred; the Englishman pleads innocence, saying that he fought only in defense of Willmore. Honorably, Antonio gives Belvile a sword, saying that he has saved Belvile from being arrested. The cavalier expresses gratitude, and Antonio reveals himself to be the son of the viceroy. Belvile reacts with dismay, now knowing that Antonio is his rival for Florinda’s hand.
Subjecting a noble and honest character to various undeserved trials and tribulations is another pattern within Restoration comedy. Antonio’s sword, meanwhile signals his masculinity, even though he is wounded and has no idea who Belvile is. In giving the sword to the Englishman, however, Antonio essentially unmans himself. Belvile’s upset when he learns that Antonio is his romantic rival increases the tangled web of identities that will persist throughout the play.
Antonio reveals why he has given Belvile the sword (even as Belvile secretly curses his name). Since the Englishman is in his debt, Antonio wishes him to fight the duel over Florinda’s honor that he has set with Don Pedro (although neither Belvile nor Antonio knows that Pedro is the opponent). Belvile is incensed both by Antonio’s desire for Florinda and by the idea of a new rival in addition to Antonio. He decides to fight in Antonio’s place in order to kill this new threat, and agrees to wear Antonio’s clothes and go by his name.
Faithful and noble himself, Belvile cannot understand why Antonio would prefer the courtesan Angelica to the pure and chaste Florinda. In agreeing to fight for Antonio against Pedro, Belvile is both adding to the confusion of identity and helping himself, since he believes that he is going to be fighting another rival for Florinda’s hand (rather than Florinda’s brother).
Antonio thanks Belvile and exits, telling him that his costume is within the house and day is near. Belvile resolves to give himself over to his fate, and exits as well to go put on his disguise.
Although Belvile is not deceitful or dishonest, he has no choice but to mask himself in order to prepare for the duel.