Ten years after the fall of Troy, the victorious Greek hero Odysseus has still not returned to his native Ithaca. A band of rowdy suitors, believing Odysseus to be dead, has overrun his palace, courting his faithful -- though weakening -- wife, Penelope, and going through his stock of food. With permission from Zeus, the goddess Athena, Odysseus' greatest immortal ally, appears in disguise and urges Odysseus' son Telemachus to seek news of his father at Pylos and Sparta. However, the suitors, led by Antinous, plan to ambush him upon his return.
As Telemachus tracks Odysseus' trail through stories from his old comrades-in-arms, Athena arranges for the release of Odysseus from the island of the beautiful goddess Calypso, whose prisoner and lover he has been for the last eight years. Odysseus sets sail on a makeshift raft, but the sea god Poseidon, whose wrath Odysseus incurred earlier in his adventures by blinding Poseidon's son, the Cyclops Polyphemus, conjures up a storm. With Athena's help, Odysseus reaches the Phaeacians. Their princess, Nausicaa, who has a crush on the handsome warrior, opens the palace to the stranger. Odysseus withholds his identity for as long as he can until finally, at the Phaeacians' request, he tells the story of his adventures.
Odysseus relates how, following the Trojan War, his men suffered more losses at the hands of the Kikones, then were nearly tempted to stay on the island of the drug-addled Lotus Eaters. Next, the Cyclops Polyphemus devoured many of Odysseus' men before an ingenious plan of Odysseus' allowed the rest to escape -- but not before Odysseus revealed his name to Polyphemus and thus started his personal war with Poseidon. The wind god Ailos then provided Odysseus with a bag of winds to aid his return home, but the crew greedily opened the bag and sent the ship to the land of the giant, man-eating Laistrygonians, where they again barely escaped.
On their next stop, the goddess Circe tricked Odysseus' men and turned them into pigs. With the help of the god Hermes, Odysseus defied her spell and metamorphosed the pigs back into men. They stayed on her island for a year in the lap of luxury, with Odysseus as her lover, before moving on and resisting the temptations of the seductive and dangerous Sirens, navigating between the sea monster Scylla and the whirlpools of Charybdis, and plumbing the depths of Hades to receive a prophecy from the blind seer Tiresias. Resting on the island of Helios, Odysseus' men disobeyed his orders not to touch the oxen. At sea, Zeus punished them and all but Odysseus died in a storm. It was then that Odysseus reached Calypso's island.
Odysseus finishes his story, and the Phaeacians hospitably give him gifts and ferry him home on a ship. Athena disguises Odysseus as a beggar and instructs him to seek out his old swineherd, Eumaeus; she will recall Telemachus from his own travels. With Athena's help, Telemachus avoids the suitors' ambush and reunites with his father, who reveals his identity only to his son and swineherd. He devises a plan to overthrow the suitors with their help.
In disguise as a beggar, Odysseus investigates his palace. The suitors and a few of his old servants generally treat him rudely as Odysseus sizes up the loyalty of Penelope and his other servants. Penelope, who notes the resemblance between the beggar and her presumably dead husband, proposes a contest: she will, at last, marry the suitor who can string Odysseus' great bow and shoot an arrow through a dozen axe heads.
Only Odysseus can pull off the feat. Bow in hand, he shoots and kills the suitor Antinous and reveals his identity. With Telemachus, Eumaeus, and his goatherd Philoitios at his side, Odysseus leads the massacre of the suitors, aided only at the end by Athena. Odysseus lovingly reunites with Penelope, his knowledge of their bed that he built the proof that overcomes her skepticism that he is an impostor. Outside of town, Odysseus visits his ailing father, Laertes, but an army of the suitors' relatives quickly finds them. With the encouragement of a disguised Athena, Laertes strikes down the ringleader, Antinous' father. Before the battle can progress any further, Athena, on command from Zeus, orders peace between the two sides.