Pisanio and Imogen are on their way to Milford Haven to meet Posthumus, as Imogen thinks. Pisanio is disturbed about leading Imogen to her death. When Imogen questions his obvious anxiety, he hands Posthumus's letter to her, in which Posthumus orders him to kill Imogen at Milford Haven for her proven adultery. Imogen asks what it means to be false to his bed: to think of him all the time, and be awakened by frightening dreams about the dangers he is in? She realizes that it is Iachimo who has been false; she suspects too that some loose Italian woman has led Posthumus astray. She herself is like a discarded garment, no longer in fashion, that must be ripped to pieces (line 53). Posthumus will bring all good seeming things into disrepute, as if they were pretended for evil purposes.
She draws Pisanio's sword and orders him to take it and kill her in accordance with Posthumus's order; she asks him to tell Posthumus later of her obedience. Pisanio refuses and tosses the sword aside. She tells him he must obey his master, and she cannot kill herself as suicide is a sin. Imogen's insistence that Pisanio kill her, as suicide is a sin, triggers a series of religious images. She throws away Posthumus's letters as "heresy" (line 82); he is one of the "false teachers" of heresy (line 85). She points out that her disobedience against her father in marrying Posthumus was very unusual; she is obedient to his order that she die. She feels sad to think how, when he is tired of his new woman, he will miss her. She asks Pisanio not to delay, since both she and Posthumus want her death.
Pisanio refuses to kill Imogen, and she asks why he has therefore wasted so much time and trouble traveling all these miles. Pisanio answers that he only wanted to win time to find a way out of his situation.
He is sure that "some villain" (line 121) has abused Posthumus into thinking Imogen is unfaithful. Imogen asks whether this could be a Roman courtesan, but Pisanio says no. He plans to announce that Imogen is dead, and to send Posthumus proof of this. He wants Imogen to return to the court, but she is reluctant because Cloten is there. Pisanio says the alternative is to leave the country. Lucius will arrive in Milford Haven tomorrow. Imogen must disguise herself as a man-he has brought male clothing for her-and live near the house where Posthumus is staying, where she can receive reports on what he is doing. She will then present herself to Lucius and ask for a job as his servant. Pisanio will go back to court in case his absence arouses suspicion that he is involved in Imogen's disappearance.
Pisanio gives Imogen the box that the Queen gave him, telling her it is medicine that will treat sea-sickness or nausea.
This is a scene of great pathos in which we sympathize with both Imogen and Pisanio. Pisanio tortures himself with his unwillingness to obey Posthumus and kill Imogen. When he shows her the letter from Posthumus, he says he does not need to draw his sword against her, because the paper "hath cut her throat already" (line 33), an image that conveys her vulnerability. Imogen is too innocent even to conceive of being false to her husband, as her bitter speech (lines 40-44) reveals.
However, Imogen's innocence does not mean she is insipid. She defends herself with great passion and fury against Posthumus's slanders. Her condemnation of Posthumus, that his "revolt" against his own apparently virtuous nature would make all good seem as if it were put on for villainous purposes, strikes us as a terrifying curse on mankind. Her rapid-fire command to Pisanio, in reply to his admission that he has not slept since he received Posthumus's order to kill her, to "Do't, and to bed then," is extraordinarily ruthless.
Imogen uses the imagery of the seasons when questioning Pisanio, asking him whether the contents of the letter he hands her are summer (happy) or winter (sad) news (lines 12-13). Pisanio compares the slander against Imogen with snake venom (lines 35, 39). Reprising the play's bird imagery, Imogen believes that a "jay of Italy" (line 49) has seduced Posthumus. A jay has brightly colored plumage, and Imogen imagines this loose woman as being painted with make-up (line 50).
In another reference to Iachimo's symbolic link with hell, Pisanio rejects Imogen's request that he kill her, protesting that his sword shall not "damn" his hand (line 74).
It is difficult to understand why Pisanio is ready to believe the claim of the Queen, whom he does not trust, that the box she gave him contains healing medicines. But the plot requires that Imogen take these potions, so we are expected to gloss over Pisanio's convenient sudden trust in the Queen.
Cymbeline: Novel Summary: Act 3 Scene 4