Gower enters, narrating the passage of time. Now Pericles is settled as a king on Tyre, Thaisa is a priestess in Ephesus, and Marina has become a young woman in Tarsus. Cleon has another daughter who spends all her time with Marina, but Cleon's daughter, now of marriageable age, does not hold up next to the nearly perfect young Marina. Marina receives all the praise, and Dionyza is wildly envious; she makes plans to murder Marina so that her daughter alone may receive praise. When Marina's nurse Lychordia dies, Dionyza is ready. She hires Leonine, a murderer.
With Gower's monologue finished, Dionyza makes Leonine swear to never tell who ordered the death of Marina. Marina enters to strew flowers on Lychordia's grave, moaning: "Ay me, poor maid, / Born in a tempest when my mother died, / This world to me is but a ceaseless storm / Whirring me from my friends" (IV.i.69-72). Dionyza notes how pale she is, and suggests she takes a walk along the sea with Leonine. Marina agrees grudgingly.
As they walk, Marina speaks of the tempest in which she was born, and what her nurse had told her of her father. Leonine tells her to say her prayers, and that he will kill her. Marina asks why Dionyza would have her killed, when she has never done a bad thing to anyone. Leonine says he doesn't know the reason, just his duty. Marina asks him to come between Dionyza and herself, and spare her, rather than killing her. Then several pirates enter, scaring Leonine. The pirates take Marina, and Leonine decides to tell Dionyza that he killed Marina and threw her in the sea.
In Myteline on the island of Lesbos, Pander, who runs the brothel, and Bawd, who supplies the prostitutes, enter with their man Boult. They discuss their need to get to women for the brothel, having already raised a number of girls to the profession. Boult goes to look in the market, and Pander and Bawd discuss retiring, since prostitution is a bad vocation.
Then Boult enters with the pirates and Marina. Pander decides to buy her, and Bawd and Marina talk. Marina wishes that Leonine had succeeded in killing her. Bawd says that she will be content to live in pleasure, with gifts from all the gentlemen. Since she is a virgin, Bawd has Boult advertise Marina in the marketplace, assuming many men will line up for the opportunity to take her virginity.
Bawd tells Marina she must not weep, as none will have a good opinion of her then. Bawd promises Boult that he will be allowed to sleep with Marina too, and sends him off to advertise her more thoroughly. Marina swears to Diana that she will stay a virgin.