Cymbeline and the Queen, who were informed of Caius Lucius's presence in Act Two, begin Act Three by meeting with the Roman ambassador. Lucius informs them that Rome is demanding an annual tribute of three thousand pounds, which the empire has levied ever since conquering Cymbeline's uncle, Cassibelan. Cymbeline tells Lucius that England will no longer pay the tribute, a sentiment that both the Queen and Cloten wax upon. Lucius regrets to inform them that they are then enemies of the Roman Empire, and that they should prepare for battle. Filled with national pride and convinced of Britain's strength, Cymbeline and his family look forward to doing so.
Meanwhile, Pisanio has just received a letter from Posthumus ordering him to kill Imogen for her perceived infidelity. Imogen comes along as he is contemplating the injustice of Posthumus's command and asks Pisanio what he is reading. Pisanio gives her a second letter from Posthumus in which he tells her to meet him in Wales, at Milford-Haven. Imogen is elated and won't listen to Pisanio's attempts to dissuade her from taking the trip too rashly.
Scene three takes us to Wales, where Belarius lives disguised under the name of Morgan with his two supposed sons, whom he calls Polydore and Cadmus and who are in actuality Guiderius and Arvigarus, Cymbeline's twin sons. Belarius was once a loyal general in the employ of Cymbeline who was falsely accused of treason. Before being banished, he stole the twin heirs, Guiderius and Arvigarus, from Cymbeline with the help of their nurse, Euriphile. These boys have been raised as Polydore and Cadmus ever since, considering "Morgan" their father and the nurse, lately deceased, their mother. Belarius notes nonetheless that the boys exhibit royal spirits, inexplicable courage, and a natural thirst to learn of the world of the court.
Nearby, around Milford-Haven, Imogen demands to know where Posthumus is. By way of explanation, Pisanio shows her Posthumus's letter, which accuses her of infidelity and orders him to kill her. Imogen is devastated by the news that Posthumus has so little faith in her. She insists that Pisanio obey his master's order to kill her, but he adamantly refuses. Instead, he tells Imogen of his plan to disguise her as a man and have her taken on as Lucius' page. Imogen agrees to the plan.
Back in England, Lucius asks for an escort to Milford-Haven and announces that thus afterward Cymbeline and Rome shall be considered enemies. Cymbeline gives him his escort and abruptly turns from his dealings with Rome to his concerns about Imogen, whom he thinks has been hiding in her room all day. Cloten discovers that she is missing, and Pisanio soon enters, only to be confronted with Cloten's rage at this development. Pisanio gives Cymbeline Posthumus's letter to Imogen, saying they should meet at Milford-Haven, meanwhile noting to himself that he'll write Posthumus and tell him that he has killed Imogen. Cloten, still obsessed with Imogen's comment that he is less worthy than Posthumus's meanest garment, forces Pisanio to give him a suit of Posthumus's clothes, planning to kill Posthumus and rape Imogen while wearing her beloved's clothes during their supposed rendezvous at Milford-Haven.
Imogen has, in the meantime, adapted to her new male identity, calling herself Fidele. Starving, she comes upon Belarius's cave, and eats the food that she finds on the table. Belarius and his "sons" return from a hunt to find a stranger in their home, but after a confrontation they realize that all parties are quite civilized. In fact, Guiderius and Arvigarus immediately sense something noble about Imogen-as she does about them-and declare that if she were a woman, they would "woo hard." In a short closing scene, the Roman Senators and Tribunes indicate that Lucius will soon lead an army of Roman gentry against England.
Many of Shakespeare's best-loved comedies, including As You Like It and A Midsummer Night's Dream, take place in two distinct locations: one urban, one rural. The two locations inevitably contrast the order and constancy of urban civilization with the fluidity of pastoral life, a clash of values that is often expressed through a cross-dressing heroine. Cymbeline, in its particular way, fits this classically Shakespearean model. Much like Rosalind in As You Like It or Viola in Twelfth Night, Imogen escapes from the unjust pressure of being a woman in a rigid, male-dominated society by taking on a false male identity in a more indeterminate environment.
A further layer of complication attends any instance of cross-dressing in Shakespeare's plays. Historically, women were not allowed to act on the stage until the Reformation, long after Shakespeare and his contemporaries had passed away. Thus, female roles in Shakespeare's plays were played by young men, often no older than boys, with fair complexions and feminine bearings. It is often difficult for a modern reader to get her or his head around this, but a cross-dressing female in Shakespeare is, effectually, a male cross-cross-dressing as a male. Gender was always already an indeterminate characteristic in any performance. Thus one can safely assume that gender-bending, so to speak, was more acceptable for an Elizabethan or Jacobean audience than it would be for ours. Cross-dressing did not inevitably pass judgment on the character who cross-dressed-it was a given facet of the theater. Likewise, cross-dressing was not an individual psychological matter, as it is often considered to be today; it was a matter of broader, cultural psychology. In other words, it is Imogen's culture, not Imogen's nature, which forces her to swap genders.
Imogen's cross-dressing also continues the theme of clothing. In taking on the clothes of a man, Imogen becomes a man. She is immediately recognized as male by Belarius and his supposed sons, and indeed in Act Five even her own husband does not recognize her beneath her masculine attire. This may seem as ludicrous as no one recognizing that Clark Kent is Superman, just because Clark is wearing glasses and a tie. And indeed, Cymbeline operates by a logic similar to that of comic books. The deeper questions in the story-questions of appearance versus identity, of historical context, and so on-are consistently expressed in naive and superficial imagery. Imogen's superficial change in clothing expresses her essential need for a change in identity following her condemnation by Posthumus; and the other characters' failure to recognize her appearance echoes their failure to recognize her virtue.