School teachers spend their careers warning students against simply summarizing the plot of a book they've been assigned to write about. True enough. You're supposed to reflect on your book, not merely know how it's ordered. But the grandest classics are not like ordinary books. When coping with them, we still have to double check the course of action -- and often we're surprised at what we have already missed -- because to fail to do so is to go on ignorant of their complexities, and so miss the point of age-old reputations and age-old lessons. By the time we soldier through Book 24 of the Iliad ("and so the Trojans buried Hector breaker of horses") we'll hope to have processed the plot accurately enough for all the worthiest personal-and-yet-universal extracts to assert themselves.
So, Book 2.
Zeus, having promised the sea-goddess Thetis that he would wreak some sort of havoc among the Greek (Achaean) troops outside Troy as vengeance for King Agamemnon having taken Achilles' woman away from him (Achilles is Thetis' son), -- lies awake on Olympus wondering how to accomplish this. He decides to send a dream to the king in the form of the Achaean wise man Nestor. The dream "Nestor" duly urges him to renew the war against Troy, because the gods have finally determined on Greek victory.
After he wakes, Agamemnon calls a council of his chiefs and tells them what has happened. All including Nestor agree that this dream must be trustworthy, and that now is the time for action. However, Agamemnon further decides that "according to time-honored custom" the troops should be tested before battle: he will announce to all of them that the siege of Troy has proved futile and that they should "cut and run."
When the king does this, the soldiers take him at his word and bolt for the ships. The goddess Hera is appalled and sends Athena down to stop the panic. The first man she goes to is Odysseus, who was furious at the panic to begin with. Commanded by Athena to calm the men, he ranges among them, exhorting his equals and lambasting the commoners to order. Last to be controlled is the strange, deformed, obscenity-spewing Thersites, who finally earns a crack on the head with Odysseus' scepter and a relieved laugh from the armies.
With Athena beside him, Odysseus now speaks to the throngs and to Agamemnon. He acknowledges that the war has been long, but reminds them of the sign given to them at a sacrifice held before they sailed for Troy -- they all witnessed the omen of a snake devouring a nest of eight fledgling birds and their mother, and of the snake then being turned to stone; they all remember the explanation of this portent was that the war against Troy would last nine years, but that the city would in the end fall.
The men are cheered by this, and Nestor echoes Odysseus' encouragement. He seems briefly to allude to Achilles' absence from the scene -- "Let them rot, the one or two who hatch their plans apart from all the troops; what good can they win from that?" -- and he advises the king to marshal the men by tribes and clans so that any cowardice among them will stand out most shamefully. Agamemnon salutes Nestor for his advice, comments briefly himself on his fight with Achilles ("imagine, I and Achilles wrangling over a girl"), and then the troops disperse to eat and make a sacrifice before battle commences.
The rest of Book 2 is a list of the legions making up the Achaean and then the Trojan army ("who were the captains of the Achaean army? Who were the kings?"). The largest Greek contingent is that from Mycenae, commanded by Agamemnon; his brother, Menelaus, leads the forces from Lacedaemon, "and his own heart blazed the most to avenge the groans and shocks of war they'd borne for Helen." Odysseus hails from Ithaca, Idomeneus from Crete. We get a glimpse of "Nireus the handsomest man who ever came to Troy," but who only commands three ships and is a lightweight. We see Achilles and his fifty ships' worth of men, out of action because of Achilles' rage at losing Briseis.
The goddess Iris now flies down from heaven to the Trojans in their assembly, demanding that the Trojan king Priam open the gates and send the army out to meet the invaders. Despite her disguise, Priam's son Hector recognizes divinity and obeys her instantly. He "breaks up the assembly," and the Trojans pour out onto the plain. They are much more quickly described, their two greatest heroes being Hector and Aeneas.