Achilles and Agamemnon have divided the coalition. Thersites, who is lame and bald, ridicules Achilles and Odysseus, and the men need to laugh because a plague has swept through the Greek camp. Smoke from the funeral pyres reaches the Trojans, who rejoice bitterly. On the tenth day of the epidemic, Achilles calls a meeting on the beach, and Calchas, a prophet, pronounces that Apollo has sent the plague as punishment for capturing Chryseis, whose father is a priest of Apollo.

This presents a challenge to Agamemnon, who grudgingly agrees to return Chryseis. The divide between Agamemnon and Achilles deepens. Achilles lacks respect for Agamemnon, who is threatened by his martial prowess. What starts as insults quickly turns to threats. Agamemnon threatens to take Achilles’s mistress Briseis, and Achilles swears an oath that he and his men will fight no longer.

Agamemnon returns Chryseis, sending Odysseus, his most diplomatic subject in the return party. The army carry out purification rites. Chryseis is returned to her father, who prays to Apollo on behalf of the Greeks. A ritual sacrifice of bulls follows, on which the worshippers feast.