The Odyssey begins after the end of the ten-year Trojan War (the subject of the Iliad), and Odysseus has still not returned home from the war because he angered the god Poseidon. Odysseus' son Telemachus is about 20 years old and is sharing his absent father's house on the island of Ithaca with his mother Penelope and a crowd of 108 boisterous young men, "the Suitors", whose aim is to persuade Penelope to marry one of them, all the while reveling in Odysseus' palace and eating up his wealth.
Odysseus' protectress, the goddess Athena, requests to Zeus, king of the gods, to finally allow Odysseus to return home when Odysseus' enemy, the god of the sea Poseidon, is absent from Mount Olympus to accept a sacrifice in Ethiopia. Then, disguised as a Taphian chieftain named Mentes, she visits Telemachus to urge him to search for news of his father. He offers her hospitality; they observe the suitors dining rowdily while the bard Phemius performs a narrative poem for them. Penelope objects to Phemius' theme, the "Return from Troy", because it reminds her of her missing husband, but Telemachus rebuts her objections, asserting his role as head of the household.
That night Athena, disguised as Telemachus, finds a ship and crew for the true prince. The next morning, Telemachus calls an assembly of citizens of Ithaca to discuss what should be done with the suitors. Telemachus is scoffed by the insolent suitors, particularly by their leaders Antinous, Eurymachus, and Leiocritus. Accompanied by Athena (now disguised as Mentor), he departs for the Greek mainland and the household of Nestor, most venerable of the Greek warriors at Troy, who resided in Pylos after the war.
From there, Telemachus rides overland, accompanied by Nestor's son Peisistratus, to Sparta, where he finds Menelaus and Helen, who are now reconciled. While Helen laments the fit of lust brought on by Aphrodite that sent her to Troy with Paris, Menelaus recounts how she betrayed the Greeks by attempting to imitate the voices of the soldiers' wives while they were inside the Trojan Horse. Telemachus also hears from Helen, who is the first to recognize him, that she pities him because Odysseus was not there for him in his childhood because he went to Troy to fight for her and also about his exploit of stealing the Palladium, or the Luck of Troy, where she was the only one to recognize him. Menelaus, meanwhile, also praises Odysseus as an irreproachable comrade and friend, lamenting the fact that they were not only unable to return together from Troy but that Odysseus is yet to return.
Both Helen and Menelaus also say that they returned to Sparta after a long voyage by way of Egypt. There, on the island of Pharos, Menelaus encountered the old sea-god Proteus, who told him that Odysseus was a captive of the nymph Calypso. Incidentally, Telemachus learns the fate of Menelaus' brother Agamemnon, king of Mycenae and leader of the Greeks at Troy: he was murdered on his return home by his wife Clytemnestra and her lover Aegisthus. The story briefly shifts to the suitors, who have only just now realized that Telemachus is gone. Angry, they formulate a plan to ambush his ship and kill him as he sails back home. Penelope overhears their plot and worries for her son's safety.
Escape to the Phaeacians
The second part recounts the story of Odysseus. In the course of his seven years in captivity of Calypso on the island of Ogygia, she has fallen deeply in love with him, even though he has consistently spurned her offer of immortality as her husband and still mourns for home. She is ordered to release him by the messenger god Hermes, who has been sent by Zeus in response to Athena's plea. Odysseus builds a raft and is given clothing, food, and drink by Calypso. When Poseidon learns that Odysseus has escaped, he wrecks the raft but, helped by a veil given by the sea nymph Ino, Odysseus swims ashore on Scherie, the island of the Phaeacians. Naked and exhausted, he hides in a pile of leaves and falls asleep.
The next morning, awakened by the laughter of girls, he sees the young Nausicaä, who has gone to the seashore with her maids to wash clothes after Athena told her in a dream to do so. He appeals to her for help. She encourages him to seek the hospitality of her parents, Arete and Alcinous (or Alkinous). Odysseus is welcomed and is not at first asked for his name, but Alcinous promises to provide him a ship to return him to his home country.
He remains for several days, and is goaded into taking part in a discus throw by the taunts of Euryalus, impressing the Phaeacians with his incredible athletic ability. Afterwards, he hears the blind singer Demodocus perform two narrative poems. The first is an otherwise obscure incident of the Trojan War, the "Quarrel of Odysseus and Achilles"; the second is the amusing tale of a love affair between two Olympian gods, Ares and Aphrodite. Finally, Odysseus asks Demodocus to return to the Trojan War theme and tell of the Trojan Horse, a stratagem in which Odysseus had played a leading role. Unable to hide his emotion as he relives this episode, Odysseus at last reveals his identity. He then begins to tell the story of his return from Troy.
Odysseus' account of his adventures
Odysseus goes back in time and recounts his story to the Phaeacians. After a failed piratical raid on Ismaros in the land of the Cicones, Odysseus and his twelve ships were driven off course by storms. Odysseus visited the lethargic Lotus-Eaters who gave his men their fruit that would have caused them to forget their homecoming had Odysseus not dragged them back to the ship by force.
Afterwards, Odysseus and his men landed on a lush, uninhabited island near the land of the Cyclopes. The men then landed on shore and entered the cave of Polyphemus, where they found all the cheeses and meat they desired. Upon returning home, Polyphemus sealed the entrance with a massive boulder and proceeded to eat Odysseus' men. Odysseus devised an escape plan in which he, identifying himself as "Nobody", plied Polyphemus with wine and blinded him with a wooden stake. When Polyphemus cried out, his neighbors left after Polyphemus claimed that "Nobody" had attacked him. Odysseus and his men finally left the cave by hiding on the underbellies of the sheep as they were let out of the cave.
While they were escaping, however, Odysseus foolishly taunted Polyphemus and revealed his true identity. Recalling that had been prophesied by appeals to his father Poseidon. Poseidon then cursed Odysseus to wander the sea for ten years, during which he would lose all his crew and return home through the aid of others. After the escape, Odysseus and his crew stayed with Aeolus, a king endowed by the gods with the winds. He gave Odysseus a leather bag containing all the winds, except the west wind, a gift that should have ensured a safe return home. Just as Ithaca came into sight, the greedy sailors naively opened the bag while Odysseus slept, thinking it contained gold. All of the winds flew out and the resulting storm drove the ships back the way they had come. Aeolus, recognizing that Odysseus has drawn the ire of the gods, refused to further assist him.
The men then re-embarked and encountered the cannibalistic Laestrygonians. All of Odysseus' ships except his own entered the harbor of the Laestrygonians' Island and were immediately destroyed. He sailed on and reached the island of Aeaea where he visited the witch-goddess Circe, daughter of the sun-god Helios. She turned half of his men into swine after feeding them drugged cheese and wine. Hermes warned Odysseus about Circe and gave Odysseus an herb called moly which gave him resistance to Circe's magic. Odysseus forced the now-powerless Circe to change his men back to their human form, and was subsequently seduced by her.
They remained with her on the island for one year, while they feasted and drank. Finally, guided by Circe's instructions, Odysseus and his crew crossed the ocean and reached a harbor at the western edge of the world, where Odysseus sacrificed to the dead. He first encountered the spirit of Elpenor, a crewman who had gotten drunk and fallen from a roof to his death on Aeaea. Elpenor's ghost told Odysseus to bury his body, which Odysseus promised to do. Odysseus then summoned the spirit of the prophet Tiresias for advice on how to appease Poseidon upon his return home, and was told that he may return home if he is able to stay himself and his crew from eating the sacred livestock of Helios on the island of Thrinacia and that failure to do so would result in the loss of his ship and his entire crew. Next Odysseus met the spirit of his own mother, Anticlea, who had died of grief during his long absence. From her, he got his first news of his own household, threatened by the greed of the Suitors. Finally, he met the spirits of famous men and women. Notably, he encountered the spirit of Agamemnon, of whose murder he now learned, and Achilles, who lamented the woes of the land of the dead but was comforted in hearing of the success of his son Neoptolemus (for Odysseus' encounter with the dead, see also Nekuia).
Returning to Aeaea, they buried Elpenor and were advised by Circe on the remaining stages of the journey. They skirted the land of the Sirens, who sang an enchanting song that normally caused passing sailors to steer toward the rocks, only to hit them and sink. All of the sailors had their ears plugged up with beeswax, except for Odysseus, who was tied to the mast as he wanted to hear the song. He told his sailors not to untie him as it would only make him want to drown himself. They then passed between the six-headed monster Scylla and the whirlpool Charybdis, narrowly avoiding death, even though Scylla snatched up six men.
Next, they landed on the island of Thrinacia, with the crew overriding Odysseus's wishes to remain away from the island. Zeus caused a storm which prevented them leaving, causing them to deplete the food given to them by Circe. While Odysseus was away praying, his men ignored the warnings of Tiresias and Circe and hunted the sacred cattle of Helios. The Sun God insisted that Zeus punish the men for this sacrilege. They suffered a shipwreck as they were driven towards Charybdis. All but Odysseus were drowned. Odysseus clung to a fig tree above Charybdis. Washed ashore on the island of Ogygia, he was compelled to remain there as Calypso's lover, bored, homesick and trapped on her small island, until she was ordered by Zeus, via Hermes, to release Odysseus. Odysseus did not realise how long it would take to get home to his family.
Return to Ithaca
Having listened with rapt attention to his story, the Phaeacians agree to provide Odysseus with more treasure than he would have received from the spoils of Troy. They deliver him at night, while he is fast asleep, to a hidden harbour on Ithaca. Poseidon, offended that the Phaeacians have returned Odysseus home, destroys the Phaeacian ship on its return voyage, and the city sacrifices to Poseidon and agrees to stop giving escorts to strangers to appease him. Odysseus awakens and believes that he has been dropped on a distant land before Athena appears to him and reveals that he is indeed on Ithaca. She then hides his treasure in a nearby cave and disguises him as an elderly beggar so he can see how things stand in his household. He finds his way to the hut of one of his own slaves, the swineherd Eumaeus, who treats him hospitably and speaks favorably of Odysseus. After dinner, the disguised Odysseus tells the farm laborers a fictitious tale of himself: he was born in Crete, had led a party of Cretans to fight alongside other Greeks in the Trojan War, and had then spent seven years at the court of the king of Egypt, finally shipwrecking in Thesprotia and crossing from there to Ithaca. He further promises the men of the return of Odysseus, but his promises are wearily discounted by the men.
Meanwhile, Telemachus sails home from Sparta, evading an ambush set by the Suitors. He disembarks on the coast of Ithaca and makes for Eumaeus's hut. Father and son meet; Odysseus identifies himself to Telemachus (but still not to Eumaeus), and they decide that the Suitors must be killed. Telemachus goes home first. Accompanied by Eumaeus, Odysseus returns to his own house, still pretending to be a beggar. When Odysseus' dog (who was a puppy before he left) saw him, he becomes so excited that he dies. He is ridiculed by the Suitors in his own home, especially by one extremely impertinent man named Antinous. Odysseus meets Penelope and tests her intentions by saying he once met Odysseus in Crete. Closely questioned, he adds that he had recently been in Thesprotia and had learned something there of Odysseus's recent wanderings.
Odysseus's identity is discovered by the housekeeper, Eurycleia, when she recognizes an old scar as she is washing his feet. Eurycleia tries to tell Penelope about the beggar's true identity, but Athena makes sure that Penelope cannot hear her. Odysseus then swears Eurycleia to secrecy.
Slaying of the Suitors
The next day, at Athena's prompting, Penelope maneuvers the Suitors into competing for her hand with an archery competition using Odysseus' bow. The man who can string the bow and shoot it through a dozen axe heads would win. Odysseus takes part in the competition himself: he alone is strong enough to string the bow and shoot it through the dozen axe heads, making him the winner. He then throws off his rags and kills Antinous with his next arrow. Then, with the help of Athena, Odysseus, Telemachus, Eumaeus, and Philoetius the cowherd he kills the other Suitors, first using the rest of the arrows and then by swords and spears once both sides armed themselves. Once the battle is won, Odysseus and Telemachus also hang twelve of their household maids whom Eurycleia identifies as guilty of betraying Penelope or having sex with the Suitors. They mutilate and kill the goatherd Melanthius, who had mocked and abused Odysseus and brought weapons and armor to the suitors. Now, at last, Odysseus identifies himself to Penelope. She is hesitant but recognizes him when he mentions that he made their bed from an olive tree still rooted to the ground. Many modern and ancient scholars take this to be the original ending of the Odyssey, and the rest to be an interpolation.
The next day he and Telemachus visit the country farm of his old father Laertes, who likewise accepts his identity only when Odysseus correctly describes the orchard that Laertes had previously given him.
The citizens of Ithaca have followed Odysseus on the road, planning to avenge the killing of the Suitors, their sons. Their leader points out that Odysseus has now caused the deaths of two generations of the men of Ithaca: his sailors, not one of whom survived; and the Suitors, whom he has now executed (albeit rightly). Athena intervenes in a dea ex machina and persuades both sides to give up the vendetta. After this, Ithaca is at peace once more, concluding the Odyssey.