Creusa enters the stage, aware that she is an enemy of the state. She claims that she has run to them from the house where the banquet was held to escape her pursuers. She asks the chorus where she might hide; they respond that she should approach the altar before the temple of Apollo, since it is against sacred law to kill a supplicant. Following this wise counsel, Creusa clings to the altar, in which lie ashes from a recently burned dedication.

As Ion approaches Creusa, she begs him to spare her life on account of her presence at the altar. Ion questions the utility of a religious law that was intended to protect innocent people, not the guilty. He wonders why such a law was ever established. Ion also accuses Creusa of duplicitousness for taking refuge at the altar of a god whose son she tried to poison. Creusa retorts that Ion is now Xuthus’s son, not Apollo’s, and that Xuthus and Ion were positioning to take over Athens from her noble ancestors. Ion rejects this accusation, disavowing any attempt at usurping the Athenian throne while also commenting that Xuthus earned his place in Athens due to his triumphs.