Joyce divided Ulysses into 18 chapters or "episodes". At first glance much of the book may appear unstructured and chaotic; Joyce once said that he had "put in so many enigmas and puzzles that it will keep the professors busy for centuries arguing over what I meant", which would earn the novel "immortality". The two schemata which Stuart Gilbert and Herbert Gorman released after publication to defend Joyce from the obscenity accusations made the links to the Odyssey clear, and also explained the work's internal structure.
Every episode of Ulysses has a theme, technique, and correspondence between its characters and those of the Odyssey. The original text did not include these episode titles and the correspondences; instead, they originate from the Linati and Gilbert schemata. Joyce referred to the episodes by their Homeric titles in his letters. He took the idiosyncratic rendering of some of the titles, e.g. "Nausikaa" and the "Telemachia". from Victor Bérard's two-volume Les Phéniciens et l'Odyssée which he consulted in 1918 in the Zentralbibliothek Zürich.
Part I: The Telemachiad
Episode 1, Telemachus
It is 8 a.m. Buck Mulligan, a boisterous medical student, calls Stephen Dedalus (a young writer encountered as the principal subject of A Portrait of the Artist as a Young Man) up to the roof of the Sandycove Martello tower where they both live. There is tension between Stephen and Mulligan, stemming from a cruel remark Stephen has overheard Mulligan making about his recently deceased mother, May Dedalus, and from the fact that Mulligan has invited an English student, Haines, to stay with them. The three men eat breakfast and walk to the shore, where Mulligan demands from Stephen the key to the tower and a loan. Departing, Stephen declares that he will not return to the tower tonight, as Mulligan, the "usurper", has taken it over.
Episode 2, Nestor
Stephen is teaching a history class on the victories of Pyrrhus of Epirus. After class, one student, Cyril Sargent, stays behind so that Stephen can show him how to do a set of arithmetic exercises. Stephen looks at the aesthetically unappealing Sargent and tries to imagine Sargent's mother's love for him. Stephen then visits school headmaster, Garrett Deasy, from whom he collects his pay and a letter to take to a newspaper office for printing. The two discuss Irish history and the role of Jews in the economy. As Stephen leaves, Deasy makes a final derogatory remark against the Jews, stating that Ireland has never extensively persecuted the Jews because they were never let in to the country. This episode is the source of some of the novel's most famous lines, such as Dedalus's claim that "history is a nightmare from which I am trying to awake" and that God is "a shout in the street."
Episode 3, Proteus
Stephen finds his way to Sandymount Strand and mopes around for some time, mulling various philosophical concepts, his family, his life as a student in Paris, and his mother's death. As Stephen reminisces and ponders, he lies down among some rocks, watches a couple and a dog, scribbles some ideas for poetry, picks his nose and urinates behind a rock. This chapter is characterised by a stream of consciousness narrative style that changes focus wildly. Stephen's education is reflected in the many obscure references and foreign phrases employed in this episode, which have earned it a reputation for being one of the book's most difficult chapters.
Part II: The Odyssey
Episode 4, Calypso
The narrative shifts abruptly. The time is again 8 am, but the action has moved across the city and to the second protagonist of the book, Leopold Bloom, a part-Jewish advertising canvasser. Bloom, after starting to prepare breakfast, decides to walk to a butcher to buy a pork kidney. Returning home, he prepares breakfast and brings it with the mail to his wife Molly as she lounges in bed. One of the letters is from her concert manager Blazes Boylan. Bloom is aware that Molly will welcome Boylan into her bed later that day, and is tormented by the thought. Bloom reads a letter from their daughter Milly Bloom. The chapter closes with Bloom defecating in the outhouse.
Episode 5, Lotus Eaters
Bloom makes his way to Westland Row post office where he receives a love letter from one 'Martha Clifford' addressed to his pseudonym, 'Henry Flower'. He meets an acquaintance, and while they chat, Bloom attempts to ogle a woman wearing stockings, but is prevented by a passing tram. Next, he reads the letter and tears up the envelope in an alley. He wanders into a Catholic church service and muses on theology. The priest has the letters I.N.R.I. or I.H.S. on his back; Molly had told Bloom that they meant I have sinned or I have suffered, and Iron nails ran in. He goes to a chemist where he buys a bar of lemon soap. He then meets another acquaintance, Bantam Lyons, who mistakenly takes him to be offering a racing tip for the horse Throwaway. Finally, Bloom heads towards the baths.
Episode 6, Hades
The episode begins with Bloom entering a funeral carriage with three others, including Stephen's father. They drive to Paddy Dignam's funeral, making small talk on the way. The carriage passes both Stephen and Blazes Boylan. There is discussion of various forms of death and burial, and Bloom is preoccupied by thoughts of his dead son, Rudy, and the suicide of his own father. They enter the chapel into the service and subsequently leave with the coffin cart. Bloom sees a mysterious man wearing a mackintosh during the burial. Bloom continues to reflect upon death, but at the end of the episode rejects morbid thoughts to embrace 'warm fullblooded life'.
Episode 7, Aeolus
At the office of the Freeman's Journal, Bloom attempts to place an ad. Although initially encouraged by the editor, he is unsuccessful. Stephen arrives bringing Deasy's letter about 'foot and mouth' disease, but Stephen and Bloom do not meet. Stephen leads the editor and others to a pub, relating an anecdote on the way about 'two Dublin vestals'. The episode is broken into short segments by newspaper-style headlines, and is characterised by an abundance of rhetorical figures and devices.
Episode 8, Lestrygonians
Bloom's thoughts are peppered with references to food as lunchtime approaches. He meets an old flame and hears news of Mina Purefoy's labour. He enters the restaurant of the Burton Hotel where he is revolted by the sight of men eating like animals. He goes instead to Davy Byrne's pub, where he consumes a gorgonzola cheese sandwich and a glass of burgundy, and muses upon the early days of his relationship with Molly and how the marriage has declined: 'Me. And me now.' Bloom's thoughts touch on what goddesses and gods eat and drink. He ponders whether the statues of Greek goddesses in the National Museum have alimentary-canal exits as do mortals. On leaving the pub Bloom heads toward the museum, but spots Boylan across the street and, panicking, rushes into the gallery across the street from the museum.
Episode 9, Scylla and Charybdis
At the National Library, Stephen explains to various scholars his biographical theory of the works of Shakespeare, especially Hamlet, which he claims are based largely on the posited adultery of Shakespeare's wife. Bloom enters the National Library to look up an old copy of the ad he has been trying to place. He encounters Stephen briefly and unknowingly at the end of the episode.
Episode 10, Wandering Rocks
In this episode, nineteen short vignettes depict the wanderings of various characters, major and minor, through the streets of Dublin. The episode ends with an account of the cavalcade of the Lord Lieutenant of Ireland, William Ward, Earl of Dudley, through the streets, which is encountered by various characters from the novel.
Episode 11, Sirens
In this episode, dominated by motifs of music, Bloom has dinner with Stephen's uncle at a hotel, while Molly's lover, Blazes Boylan, proceeds to his rendezvous with her. While dining, Bloom watches the seductive barmaids and listens to the singing of Stephen's father and others.
Episode 12, Cyclops
This chapter is narrated by an unnamed denizen of Dublin. The narrator goes to Barney Kiernan's pub where he meets a character referred to only as "The Citizen". When Leopold Bloom enters the pub, he is berated by the Citizen, who is a fierce Fenian and anti-Semite. The episode ends with Bloom reminding the Citizen that his Saviour was a Jew. As Bloom leaves the pub, the Citizen, in anger, throws a biscuit tin at Bloom's head, but misses. The chapter is marked by extended tangents made in voices other than that of the unnamed narrator: these include streams of legal jargon, Biblical passages, and elements of Irish mythology.
Episode 13, Nausicaa
Gerty MacDowell, a young woman on Sandymount strand, contemplates love, marriage and femininity as night falls. The reader is gradually made aware that Bloom is watching her from a distance, and as she exposes her legs and underwear to him it is unclear how much of the narrative is actually Bloom’s sexual fantasy. Bloom’s masturbatory climax is echoed by the fireworks at the nearby bazaar. As Gerty leaves, Bloom realises that she has a lame leg. After several digressions of thought he decides to visit Mina Purefoy at the hospital. The style of the first half of the episode borrows from (and parodies) romance magazines and novelettes.
Episode 14, Oxen of the Sun
Bloom visits the maternity hospital where Mina Purefoy is giving birth, and finally meets Stephen, who is drinking with Buck Mulligan and his medical student friends. They continue on to a pub to continue drinking, following the successful birth of the baby. This chapter is remarkable for Joyce's wordplay, which, among other things, recapitulates the entire history of the English language. After a short incantation, the episode starts with latinate prose, Anglo-Saxon alliteration, and moves on through parodies of, among others, Malory, the King James Bible, Bunyan, Defoe, Sterne, Walpole, Gibbon, Dickens, and Carlyle, before concluding in a haze of nearly incomprehensible slang.
Episode 15, Circe
Episode 15 is written as a play script, complete with stage directions. The plot is frequently interrupted by "hallucinations" experienced by Stephen and Bloom—fantastic manifestations of the fears and passions of the two characters. Stephen and Lynch walk into Nighttown, Dublin's red-light district. Bloom pursues them and eventually finds them at Bella Cohen's brothel, where in the company of her workers including Zoe Higgins, Florry Talbot and Kitty Ricketts he has a series of hallucinations regarding his sexual fetishes, fantasies, and transgressions. Bloom is put in the dock to answer charges by a variety of sadistic, accusing women including Mrs Yelverton Barry, Mrs Bellingham and The Hon Mrs Mervyn Talboys. When Bloom witnesses Stephen overpaying for services received, Bloom decides to hold onto the rest of Stephen's money for safekeeping. Stephen hallucinates that the rotting cadaver of his mother has risen up from the floor to confront him. Terrified, Stephen uses his walking stick to smash a chandelier and then runs out. Bloom quickly pays Bella for the damage, then runs after Stephen. Bloom finds Stephen engaged in a heated argument with an English soldier, Private Carr, who, after a perceived insult to the King, punches Stephen. The police arrive and the crowd disperses. As Bloom is tending to Stephen, Bloom has a hallucination of Rudy, his deceased child.
Part III: The Nostos
Episode 16, Eumaeus
Bloom and Stephen go to the cabman's shelter to restore the latter to his senses. At the cabman's shelter, they encounter a drunken sailor named D. B. Murphy (W. B. Murphy in the 1922 text). The episode is dominated by the motif of confusion and mistaken identity, with Bloom, Stephen and Murphy's identities being repeatedly called into question. The rambling and laboured style of the narrative in this episode reflects the nervous exhaustion and confusion of the two protagonists.
Episode 17, Ithaca
Bloom returns home with Stephen, makes him a cup of cocoa, discusses cultural and lingual differences between them, considers the possibility of publishing Stephen's parable stories, and offers him a place to stay for the night. Stephen refuses Bloom's offer and is ambiguous about Bloom's proposal of future meetings. The two men urinate in the backyard, Stephen departs and wanders off into the night, and Bloom goes to bed, where Molly is sleeping. She awakens and questions him about his day. The episode is written in the form of a rigidly organized and "mathematical" catechism of 309 questions and answers, and was reportedly Joyce's favourite episode in the novel. The deep descriptions range from questions of astronomy to the trajectory of urination and include a famous list of 25 men perceived as Molly's lovers (apparently corresponding to the suitors slain at Ithaca by Odysseus and Telemachus in The Odyssey), including Boylan, and Bloom's psychological reaction to their assignation. While describing events apparently chosen randomly in ostensibly precise mathematical or scientific terms, the episode is rife with errors made by the undefined narrator, many or most of which are volitional by Joyce.
Episode 18, Penelope
The final episode consists of Molly Bloom's thoughts as she lies in bed next to her husband. The episode uses a stream-of-consciousness technique in eight sentences and lacks punctuation. Molly thinks about Boylan and Bloom, her past admirers, including Lieutenant Stanley G. Gardner, the events of the day, her childhood in Gibraltar, and her curtailed singing career. These thoughts are occasionally interrupted by distractions, such as a train whistle or the need to urinate. The episode famously concludes with Molly's remembrance of Bloom's marriage proposal, and of her acceptance: "he asked me would I yes to say yes my mountain flower and first I put my arms around him yes and drew him down to me so he could feel my breasts all perfume yes and his heart was going like mad and yes I said yes I will Yes."