mole on Imogen's breast, he wins the wager, and Posthumus leaves, furious at what he perceives as the deceitful nature of women.

Act III
Cymbeline meets with Caius Lucius and firmly tells him that he will not pay tribute to Rome. Caius Lucius then declares war on Britain. Pisanio receives two letters from Posthumus. The first letter tells Imogen that Posthumus will soon be at Milford-Haven in Wales and that she can meet him there if she wishes. The second letter instructs Pisanio to kill Imogen at Milford-Haven because she has been unfaithful to Posthumus.

Outside a cave in Wales, we are introduced to Belarius, a lord banished by Cymbeline twenty years earlier based on false accusations. Belarius now goes by the name Morgan. We also meet Guiderius and Arviragus, Cymbeline's two sons who were abducted by Belarius when they were infants. Guiderius and Arviragus, believed to be Belarius/Morgan's sons, are called Polydore and Cadwal respectively. They set off to hunt for their dinner.

Pisanio and Imogen have also arrived in Wales. Pisanio reveals to Imogen the letter containing Posthumus's orders to kill her. Imogen urges Pisanio to execute the command immediately, but Pisanio has a different idea. He has brought men's attire for Imogen and proposes that she disguise herself as a man to secure passage with Caius Lucius when he departs from Britain. He hands her the drug given to him by the queen, falsely informing her that it is a remedy for fatigue and illness.

When Imogen is discovered missing from Cymbeline's court, the king is furious, and Cloten confronts the recently returned Pisanio, demanding to know Imogen's whereabouts. Pisanio provides Cloten with a letter suggesting that Imogen will meet Posthumus at Milford-Haven. Cloten coerces Pisanio into serving him, to which Pisanio reluctantly agrees, only to placate Cloten temporarily. Pisanio's first task is to bring Cloten some of Posthumus's clothes.

Meanwhile, disguised as a man, Imogen travels for two days until hunger leaves her too weak to continue. She enters Belarius's cave and consumes some of the food there. Belarius, along with Cymbeline's two sons, discovers her when they return from hunting. Though initially fearful, Imogen is treated kindly by Belarius, and Guiderius and Arviragus, ironically, pledge to treat her as a brother. In the final scene, two Roman senators briefly discuss war preparations against England.

Act IV
In the morning, Belarius, Guiderius, and Arviragus leave their cave to go hunting. Imogen stays behind because she is unwell. After they depart, she takes some of the medicine given to her by Pisanio. Outside the cave, Belarius and Cymbeline's sons encounter Cloten, who has arrived there using directions from Posthumus's letter to Imogen. Belarius recognizes Cloten from years ago, and he and Arviragus step aside to see if Cloten is alone, while Guiderius faces Cloten directly. Cloten, assuming Guiderius is a rogue mountaineer, threatens him. They fight, and Guiderius kills Cloten, decapitating him. Arviragus returns to the cave and mistakenly believes Imogen is dead. Belarius, Guiderius, and Arviragus place her body next to Cloten's headless corpse, planning to return at midnight to cover the bodies with dew-drenched flowers. Meanwhile, Imogen awakens, sees the headless body dressed in Posthumus's clothes, and assumes it is Posthumus. She immediately suspects that Pisanio, in collusion with Cloten, is responsible for Posthumus's death, believing he forged the letters and misled her about the medicine. She throws herself onto the corpse, weeping. Caius Lucius and his military officers, preparing to receive troops from the continent for war with the English, discover her in this state. Caius Lucius believes Imogen is a devoted page mourning his master, and for her safety, she pretends to be. She tells the Roman general that her name is Fidele and that her deceased master was Richard du Champ. Impressed by her loyalty, Caius Lucius asks her to join his service.

At Cymbeline's palace, the queen is ill with worry over Cloten, and the king also misses Cloten's presence as war looms. Cymbeline threatens to torture Pisanio, thinking he knows where Imogen has gone. Pisanio insists he knows nothing and plans to redeem himself by fighting valiantly in the upcoming battles. A lord from Cymbeline's court supports Pisanio, asserting that Pisanio was at the court on the day Imogen disappeared.

Back in Wales, Guiderius and Arviragus are eager to join the English forces and fight the Romans. Belarius is reluctant, fearing recognition. However, he eventually succumbs to the persistent enthusiasm of his two young wards.

Act V
Posthumus receives a blood-stained cloth and assumes that Pisanio has sent it as evidence of Imogen’s murder, as he had instructed. He immediately regrets his orders and feels he must die to atone for his role in her death. He has come to Britain with a group of Italian nobles led by Jachimo to fight against the Britons, but he disguises himself as an English peasant and fights alongside the Britons against the Romans. Initially, the Roman forces overpower the English, and Cymbeline is captured as the English troops retreat. However, Belarius, Guiderius, and Aviragus rescue Cymbeline and make a courageous stand, halting the English retreat. Posthumus joins their effort and fights with reckless abandon, hoping to die in battle. He duels Jachimo and disarms him. The English emerge victorious, and Belarius, Guiderius, and Aviragus are celebrated for their bravery. Cymbeline searches for the fourth hero—Posthumus disguised as a peasant—but cannot find him to reward him. Posthumus has changed back into a Roman soldier’s uniform and is subsequently arrested and jailed. While imprisoned, the spirits of his deceased family members visit him in a dream, pleading with Jupiter to show mercy and reward Posthumus for his noble deeds. Jupiter, descending on an eagle, is irritated by the ghosts' pleas and commands them to return to the underworld, asserting that mortal lives are his domain. Before leaving, Jupiter places a tablet with a cryptic prophecy on Posthumus’s sleeping body. The ghosts place the tablet on him and disappear. When Posthumus awakens, he is puzzled by the writing. Soon after, he and other Roman prisoners are brought to Cymbeline’s tent. Cymbeline learns from Cornelius that the queen has died after confessing her plans to poison both him and Imogen to make Cloten king. Cymbeline decrees that all Roman prisoners must die. Caius Lucius requests mercy for his page—actually Imogen in disguise—and Cymbeline agrees. Imogen, noticing Posthumus’s diamond ring on Jachimo’s finger, is allowed to question him. Jachimo confesses his deceit and villainy concerning Posthumus and Imogen. All deceptions and misunderstandings come to light, with Posthumus, Pisanio, and Cornelius revealing their parts in the events, and Imogen’s true identity is unveiled. Guiderius admits to killing and beheading Cloten. Cymbeline condemns him to death for the treasonous act of killing a prince, but Belarius reveals that Guiderius and Aviragus are actually Cymbeline’s sons, kidnapped by Belarius twenty years earlier. Cymbeline is overwhelmed yet overjoyed by these rapid revelations. Philarmonus, the Roman soothsayer, interprets Jupiter’s tablet, which foretold the reunion of Cymbeline’s family and the improved relations between Rome and England. Cymbeline pardons the Roman prisoners and announces he will resume paying tribute to Rome, a payment he had previously withheld at the queen’s urging.