A Messenger enters, reeling from something terrible that he has seen. The Chorus presses him to reveal what has happened, intuiting that either Atreus or Thyestes is responsible.

In a long and ornate speech, the Messenger describes how Atreus took Thyestes’s sons to a recessed grove in his palace, where he killed them and cooked them before serving them as a meal to their unsuspecting father. Now, even the sun has retreated in its course in horror. The Chorus sings the fourth and final ode, in which they lament The Overturning of the Natural Order. They note that the firmament has departed from its usual cycles and wonder if this presages the destruction of the world.

Atreus delivers a joyful soliloquy in which he celebrates his kingship and compares himself to the gods: He has triumphed over his brother, and now all that remains is to reveal to him that he has eaten his own sons. Thyestes, meanwhile, rejoices as well at the apparent end of his painful exile. Even as he tries to enjoy his feast, however, he cannot help but feel sorrow and fear.