The epic begins with the assembly of the gods on Mount Olympus, where Athena pleads for the release of Odysseus from the nymph Calypso, who has detained him for seven years on her island. Meanwhile, in Ithaca, Odysseus's palace is overrun by arrogant suitors who consume his wealth and pressure his faithful wife, Penelope. Encouraged by Athena, young Telemachus sets out on a voyage to Pylos and Sparta to seek news of his missing father from Nestor and Menelaus. Through council scenes and travels, the narrative establishes the plight of the Ithacian royal house and sets the stage for the hero's eventual return.
Following the divine decree, Calypso reluctantly permits Odysseus to build a raft and depart. However, the god of the sea, Neptune, still enraged by Odysseus blinding his son the Cyclops, unleashes a violent tempest that shatters the vessel. Washed ashore on the island of Phæacia, the exhausted hero is aided by the princess Nausicaa and welcomed by King Alcinous. During elaborate banquets and athletic games, the court bards sing of the Trojan War, eventually moving Odysseus to tears and prompting him to reveal his true identity and recount his astonishing adventures.
Odysseus begins his extended flashback by describing the aftermath of Troy, detailing encounters with the lotus-eaters and the horrific battle with the man-eating giant Polyphemus. He narrates subsequent disasters, including the tragic loss of his fleet among the Laestrygons and his prolonged detention by the enchantress Circe, who transforms his crew into swine before yielding to his power. To learn the path home, Odysseus must journey into the gloomy underworld, where he converses with the prophet Tiresias, his deceased mother, and fallen comrades like Agamemnon and Achilles, receiving crucial warnings about the trials yet to come.
The narrative resumes its forward momentum as Odysseus successfully navigates the perilous waters between the monster Scylla and the whirlpool Charybdis, and resists the fatal allure of the Sirens' songs. Despite strict warnings, his exhausted companions slaughter the sacred cattle of the Sun god on the island of Trinacria, provoking divine retribution that destroys the remaining ship and crew in a violent storm. Surviving alone on a floating mast, Odysseus finally drifts to safety. With the generous assistance of the Phæacians, he is transported back to his homeland in a magical sleep, setting up the final confrontation with the suitors who have plagued his home for a decade.