Gower comes onstage and addresses the audience, saying that he has donned mortal flesh for the purpose of telling a diverting story. He tells of the setting in Antiochus, a city in Syria where King Antiochus rules. His sources, he says, relate that the king's wife died, leaving a daughter so attractive that the king took a liking to her, and enticed her to incest. Eventually young princes began approaching the king to request marriage with his daughter; in order to keep her for himself, he made a law that whoever asked for her hand had to answer a riddle correctly or face execution. Many have already tried and died. Gower exits.
King Antiochus and Pericles, the Prince of Tyre come on stage. Antiochus asks Pericles if he understands the danger he places himself in by trying the riddle, and Pericles says he does. Antiochus's daughter enters, and Pericles speaks of her apparent virtues: "Her face the book of praises, where is read nothing but curious pleasures" (I.i.58-9). Antiochus reminds Pericles of the other princes who tried the riddle and died, but Pericles says that he is ready to die if he must. Antiochus, frustrated at the willingness of Pericles to throw away his life, hurls the written riddle on the floor. Antiochus's daughter wishes him well.
Pericles reads the riddle and realizes that it refers to Antiochus's daughter finding a father and lover in the same body. Recognizing that the secret of the court, and the riddle, is incest, Pericles rejects his feelings for Antiochus's daughter. When Antiochus asks for Pericles's answer, Pericles says that he knows the truth, but it is a truth that is better kept concealed. Antiochus understands that Pericles has unraveled the riddle but does not publicly admit it. Thus Pericles is doomed to die, having not answered the riddle correctly--but Antiochus allows him forty days before his sentence will be completed. The court departs, leaving Pericles alone.
Pericles speaks with scorn of the sinful incest between Antiochus and his daughter, and thinks that surely his life is in danger if he remains in Antioch, now that he knows the truth. He determines to flee the city, and exits.
Antiochus enters and admits that he wants Pericles's head, before Pericles tells his secret to the world. Thaliart enters, and Antiochus offers him gold to kill the Prince of Tyre. They receive news that Pericles has fled. Antiochus tells Thaliart to hurry after him, and Thaliart exits. Antiochus concludes, saying he will not be calm until Pericles is dead.
The manuscript of Pericles is unique in that there is no known version of the play that draws directly on an authorial manuscript of a transcript of it, such as a promptbook. Hence the play as we have it in the First Quarto was probably reconstructed from reports of actors or spectators. Certain editors choose to follow the scene numbers of the First Quarto, wherein the play has 22 separate scenes, and others (including this SparkNote) insert the more standard Act, Scene framing.