The scene opens outside a house in Trachis where Heracles’ wife Deianeira is staying. She enters with the Nurse and laments her circumstances. After saving Deianeira from the river god Achelous, Heracles married her, but since then, he has been frequently away, fulfilling his labors. She is tormented and afraid, not knowing where he is and worried about the prophecy from an oracle he told her before he left. The nurse suggests Deianeira send Hyllus, her son with Heracles, to find out what has happened to his father.

Hyllus enters and reports that he has heard Heracles was serving a woman in Lydia but has escaped and is now waging war against Euboea. Deianeira tells Hyllus about the prophecy, which says that Heracles will be able to live out his life happily after he takes his prize and asks him to go to his father. Hyllus agrees.

The Chorus enters and sings its first song (the Parodos). They ask the sun to bring news about Heracles’ whereabouts. They describe Deianeira’s expectation of a disastrous fate and Heracles’ toils, protected by “some god” (100). They oppose Deianeira’s grieving, noting that Zeus dispenses joy and pain together. They conclude by encouraging her to hope, asking whether Zeus has ever failed “to care for his children” (100).