Denianeira is waiting in Trachis for the return of her husband Heracles from battle. Her anxiety is intensified by the fateful prophecy that if Heracles returns within a certain time then his life thereafter will be untroubled.
The atmosphere of uncertainty dissolves when the glad tidings reach Denianeira that Heracles’ homecoming is victorious. As spoils, he brings with him women captured in Oechalia, the city that he has conquered and sacked. Among them, Denianeira notices a beautiful and enigmatic figure. She is distraught to discover that this is Princess Iole and that Heracles laid siege to Oechalia as a result of his passion for her. In an attempt to rekindle her husband’s love for her, Denianeira sends him the gift of a robe smeared with the blood of the Centaur Nessus. It is a gift, however, that will bring about not reconciliation, but his painful death.
Once again, the old prophecies reveal their precise meaning after the events that they foretell have come to pass.
 
Women of Trachis, one of Sophocles’ most neglected plays, was probably staged between 457 and 430 BC.
The central theme of the play, as reflected in its two-part structure, is the finite nature of human awareness: the incapability of grasping the whole, and being able to see only one side of something.
Ignorance prevents people from having full control of their choices, so that they become aware of their fate only once it is too late.