In the Aeneid, the Trojan horse is a trap: the Greeks build an enormous horse of fir, hide chosen warriors in its belly, pretend to offer it to the gods, and sail away, and a Greek left behind, Sinon, persuades the Trojans to drag it inside the walls. At night, the warriors come out, kill the sentries, and open the gates.
Aeneas himself tells the story, at Dido's request: "you order, queen, that I renew an unspeakable grief." The Trojans are divided before the horse. The priest Laocoön runs down and warns: "I fear the Danaans, even when they bring gifts," and he drives his spear into the flank of the wood, which rings hollow. Sinon, captured on purpose, weeps and swears that the horse is an offering to Minerva, made so huge that it cannot pass through the gates. The story is believed, and two serpents come out of the sea and kill Laocoön and his sons, which the people take as punishment.
The Trojans open the wall. The horse stumbles four times on the threshold, and the arms clash in its belly, but they press on, "forgetful and blind with fury." Cassandra prophesies, and by the god's command she is never believed. Aeneas does not exempt himself from the blame: he says "we pressed on," in the plural. The text sustains two readings, naivety or the weariness of ten years of siege, and Sinon's tale offers precisely the end of the war that the city wanted to hear.
During sleep, Hector appears to Aeneas and tells him to flee and take the Penates, to found walls after crossing the sea. Aeneas wakes and fights, sees Priam die before the altar, and wants to kill Helen, until Venus shows him that it is the gods, Neptune, Juno, and Pallas, who are tearing the city down. After a sign, Anchises agrees to leave, and Creusa is lost on the way. The book ends with Aeneas carrying his father toward the mountain.