The Achaeans sack a Trojan-allied town and capture two maidens: Chryseis, whom Agamemnon, the commander, takes as his prize, and Briseis, whom Achilles, the greatest of warriors, claims. As a vengeful move by Chryses and Apollo, a plague befalls the camp. Achilles tells his mother, Thetis, to ask Zeus to punish the Achaeans while Achilles sits out of battles.
Agamemnon tests the courage of his troops by telling them that he has decided to give up the war and return to Greece, which they eagerly agree to. Athena inspires Odysseus to restore the confidence of the troops by telling them of a prophesy: nine years after the start of the war, the Achaeans will take Troy.
Books 3 & 4
Paris, the prince who started the war by stealing Helen from her husband, Menelaus, agrees to fight Menelaus. During their battle, Aphrodite whisks Paris away to Priam’s palace and Agamemnon insists that Menelaus has won the duel. The gods overlooking the events engage in their own duels.
Books 5 & 6
When Pandarus wounds Diomedes, Athena grants Diomedes superhuman strength and the power to discern gods on the battlefield, with the caveat that he must not challenge any god except for Aphrodite. After he wounds Apollo, he breaches the agreement he made, and Ares, along with the help of the gods, aids the Trojans in taking the upper hand. Hera and Athena intervene on behalf of the Achaeans, until Diomedes wounds Ares. With the gods absent, the Achaean forces overwhelm the Trojans.
Books 7 & 8
Great Ajax is chosen to battle Hector, but Zeus calls it off, and both sides agree to observe a day of respite to bury their respective dead. Zeus then turns the tide of battle in the Trojans’ favor, and Hector drives the Achaeans back into their fortifications. Zeus notes that only Achilles can prevent the Achaeans’ destruction.
Books 9 & 10
As the Achaeans’ morale dwindles, Nestor urges Agamemnon to reconcile with Achilles. Achilles rejects Agamemnon’s offer and refuses to fight in the battles. Diomedes and Odysseus are sent to spy on the Trojans when they encounter Dolon, Hector’s spy, who—hoping to save his life—tells them the positions of the Trojans and all their allies. Diomedes kills Dolon, and with Odysseus, they attack a camp.
Books 11 & 12
Hector charges the Achaean line, making them panic, until Odysseus and Diomedes imbue them with fresh courage. Achilles sends his companion Patroclus to speak with Nestor, who tells Patroclus about the wounds the Trojans have inflicted upon the Achaeans, and he begs Patroclus to either persuade Achilles to rejoin the battle, or to enter the battle himself disguised in Achilles’s armor.
Books 13 & 14
After Poseidon reinvigorates the Achaean forces, the Trojans are forced to retreat. Hera assists the Achaeans by consorting with Aphrodite and the embodiment of Sleep to subdue Zeus long enough for her to tell Poseidon that he has free rein to steer the Achaeans to victory. Great Ajax knocks Hector out of the battle.
Books 15 & 16
Apollo intervenes on the Trojans’ behalf and Hector drives his forces into the Achaean camp. Patroclus goes to Achilles’s tent and begs to be allowed to wear Achilles’s armor, which Achilles agrees to as long as Patroclus only fights long enough to save the ships. Patroclus enters the battle, shifting the tide of war, but Patroclus disobeys Achilles’s order and follows the Trojans to their gates, where Apollo injures him enough for Hector to kill him.
Books 17 & 18
A struggle over Patroclus’s body ensues between the Achaean and Trojan forces, their respective gods aiding them in turn. When Achilles learns of Patroclus’s death, he loses himself, and goes to speak with his mother, who promises him a new set of armor. Achilles lets loose an enormous cry that sends the Trojans fleeing. Each army holds an assembly to plan its next move.
Books 19 & 20
After Achilles and Agamemnon reconcile, Achilles suggests going into war at once, but Odysseus persuades him to let the army eat first. Zeus allows the gods to intervene, but they decide to stand back to see how the mortals fare on their own, except for Apollo who urges Aeneas to challenge Achilles. Poseidon saves Aeneas, and Hector tries to challenge Achilles until Apollo is forced to save Hector.
Books 21 & 22
As Priam sees the human carnage on the battlefield and opens the gates of Troy, Achilles attempts to pursue them into the city when he is stopped by Apollo disguised as a Trojan prince. Hector, tricked by Athena, is goaded into facing Achilles, and since Achilles knows the weak points of Hector’s armor, he pierces his spear through Hector’s throat.
Book 23 & 24
Achilles continues mourning Patroclus, hosting games in his honor, and dragging Hector’s corpse around Patroclus’s body, until Thetis tells Achilles he must let Hector’s body be ransomed. While sleeping in Achilles’s tent, Priam places Hector’s body in a chariot and sneaks out of the camp. In Troy, grief over Hector’s death ensues.