The two "gentlemen" of the title are Proteus and Valentine, who are taking leave of one another as the play opens. Valentine travels to Milan, where he falls in love with Silvia, daughter of the Duke. Proteus, meanwhile, hunts after love and remains in Verona, pledged to faithfulness to his beloved Julia.
When Proteus travels to Milan, however, he too falls in love with Silvia and proceeds to undermine his friend by denouncing him to the Duke. Valentine is banished to the forest, where he joins a band of thieves. Proteus pursues Silvia more and more fervently, even to the point of threatening to take her violently. Julia arrives in Milan disguised as a page and joins herself to the unsuspecting Proteus, and the two of them "rescue" Silvia from the brigands to whom she had fled. At the moment when Proteus is about to attack Silvia, Valentine intercedes to save her. Astonishingly, Valentine is so overcome by his friend's anguish that he is even prepared to yield Silvia to Proteus. Julia swoons, and the page's true identity is revealed. Proteus now sees her as his true love, and the Duke arrives on stage to offer his daughter's hand to Valentine.