Gower, a poet, appears to set the stage for Act I.
Antiochus, a king, establishes Antioch, a city in Syria. He takes a wife who dies leaving behind a beautiful daughter whom the father takes a fancy to and vice-versa. Custom renders their sin a non-issue. To preserve his abominable arrangement and prevent his daughter from marrying an eligible bachelor, Antiochus contrives every suitor to enter into a bargain which invariably leads the suitor to his death: Every suitor is presented with a riddle which if he solves will win him the King’s daughter and which if he fails to solve will cost him his head.
Pericles, the Prince of Tyre, has come to Antioch to ask for the King’s (Antiochus’) daughter’s hand in marriage. When the King’s daughter, regaled in a bride’s gown, is presented, Pericles eulogizes her beauty. All the same, Antiochus reminds Pericles of what he is getting himself into, that it isn’t too late to withdraw his suit and thereby save his life which in all probability will meet the fate of all the suitors that have come before: death by beheading. Undaunted, Pericles avers that he is willing to risk losing his life for the sake of wiving the King’s daughter. And so Pericles is presented with the riddle which he reads only to be horrified by what it portends: Antiochus has been carrying on an incestuous affair with his daughter! Keeping his cool as best he can, Pericles tells the King that a sin that’s been kept a secret ought to remain so lest its disclosure lead to wholesale destruction. The King, sensing Pericles’ alarm to mean that Pericles has solved the riddle; that the King’s secret is out; that the life the King knows is in ruins unless Pericles is killed, tries to put Pericles at ease by pretending that he--Antiochus--doesn’t know that Pericles knows what the riddle means. He tells Pericles that he will have an additional forty days to solve the riddle.
Knowing that his life is in peril, Pericles flees Antioch which prompts the King to hire an assassin.
Because he has returned to Tyre and the comforts of home, thus putting himself at a safe distance from Antiochus, Pericles ought to have been happy and cheerful. That he is fretful, even angry, concerns Helicanus, a lord of Tyre, who urges his Prince to give his fretfulness and anger full expression even if that means dealing Helicanus a fatal blow with an axe. Thus persuaded, Pericles tells Helicanus of what had transpired at Antioch, of his discovery of Antiochus’ abomination. He explains that what is worrying him sick is the possibility that Antiochus would invade Tyre under a false pretext, subjecting Tyrians to an undeserving fate if only to gag Pericles from divulging Antiochus’ black secret. Under these circumstances, doesn’t it seem only right that Pericles fret and be agitated? Ever the wise counselor, Helicanus offers the following remedy: Go abroad and stay away from Tyre, leaving the governing of Tyre to a trusted deputy, until Antiochus either forgets about the whole matter or until time and old age deprives Antiochus of his mortal life. Pericles decides to adopt the plan. He will go to Tharsus, deputizing Helicanus as Tyre’s acting governor.
Lord Thaliard arrives at Tyre. He has been hired by his King, Antiochus, to find and assassinate Pericles though he is ignorant of the reason why. He is reflecting on his duty, of how if he fails to perform it he himself will be executed when he stumbles onto Helicanus who is explaining Pericles’ absence to the lords of Tyria. Helicanus explains that their Prince is on his way to Antioch to seek forgiveness of Antiochus for committing some sort of offense. Relieved that his life is no longer in peril (after all the King himself will now dispose of Pericles’ life), Thaliard announces his presence and greets Helicanus. Helicanus greets Thaliard and welcomes him to Tyre.
To distract themselves from their woes, Cleon, the governor of Tharsus, proposes that he and his wife, Dionyza, tell stories of other woes that might prove instructive. At first, Dionyza is reluctant, arguing that talking about other woes would only exacerbate theirs but Cleon persuades her otherwise, arguing that their stories will function like prayers. And so Cleon relates the sad story of Tharsus, of how at first it was a thriving, prosperous city that was the envy of the world only to be laid low by misfortune to the extent people draw lots to decide who will die first so that the living may yet survive on the meager supply of food. Cleon is thus lamenting the sad fate of Tharsus when a subordinate interrupts to report a fleet of proud ships in the offing. He reports that if the white flags they’re displaying are any indication, then they come with good intent. Cleon is pessimistic, however, and resigns himself to the possibility that the white flags are a ruse to conquer Tharsus.
Anon, Pericles proves Cleon’s pessimism to be unfounded. He has brought Tharsus a supply of corn which will be its salvation. In return, Pericles only asks to be provided with temporary asylum, which he is granted without a moment's fuss.