Jack wakes up in San Francisco, hung-over. He missed meeting Monsanto, who was going to drive him to a cabin in Big Sur.
Realizing that he needs to make a quick move, Jack decides to escape the city. He takes a bus to Monterey and walks to the cabin from there.
When he arrives, Jack is terrified by the landscape, particularly the bridge. He sleeps next to the creek.
The next day he sees Alf the sacred mule and remembers his dream about Mount Mien Mo.
When he finally gets to the cabin, Monsanto drives him back to Monterey for food and supplies and then leaves him alone.
Jack thoroughly enjoys his time in the cabin. At night he sits by the beach and writes down the sounds of the sea, a work that later becomes the poem, "Sea." He sleeps well and is calmed by his solitude.
One day Jack experiences what he calls "a signpost" of something sinister to come. He takes a deep breath one day by the water and ends up feeling dizzy. He realizes that he is going to die and it frightens him. He goes to the sea; in his mind, the water tells him it doesn't want him there.
After three weeks, Jack leaves Big Sur. He tries to hitchhike but can't get a ride. That he can't get picked up prompts him to reflect on the ways America has changed since the days of On the Road. He finally makes it to Monterey, though his feet are blistered and bloody by the time he gets there.
In San Francisco, Monsanto delivers the news that Jack's cat back home has died. Jack is devastated by the news.
They meet up with some other characters, including Ben Fagan, Dave Wain, and Ron Blake. Everyone drinks; Jack pays.
Jack calls Cody, and they head to see him in Dave's jeep. On the way there, Jack thinks he sees a flying saucer in the sky.
At Cody's house Jack laments that he doesn't have the time alone to talk to his friend like he used to. He tells everyone about Evelyn and Billie. They all watch Cody recap tires.
Jack meets Joey, and decides he is Jesus.
They all drive to see George Baso in the hospital. Jack can't believe that his friend might die.
Jack goes out driving with Bruce, the greatest driver in the world.
Everyone drinks and passes out on the floor. The next morning, Cody calls up Jack and asks him to drive back and lend him a hundred dollars. Jack is more than happy to do so. They make plans to come back to San Francisco together afterwards.
Jack ends up bringing Cody, Arthur Ma, and the others to Monsanto's cabin in the woods, where they meet up with McLear.
Jack concludes that the cabin is the sort of place where you have to be alone.
Jack and Arthur get drunk together and try to communicate via a serious of random word and phrase associations.
The men have a wood-chopping contest; Jack thinks you can judge a man's character by the way he chops wood.
They group goes to Nepenthe and drinks. Jack meets a general whom he finds to be sinister.
Jack ends up alone on the beach, drunk and still drinking, with Ron Blake. He has a manic episode of sorts and is ashamed afterwards to realize that Ron witnessed the whole thing. He sleeps.
When everyone else leaves to get more alcohol and supplies, Jack remains alone at the cabin. But when Patrick comes back, Jack enjoys talking to him so much he realizes that, as much as he claims to need his solitude, he actually loves people.
Cody shows up with his family and appears to Jack as a golden angel from heaven.
Jack talks a bit about Cody and his relationship with women, as well as the triangular situation between Jack, Cody and Evelyn.
Cody brings them all to a play that Evelyn has been working on; Jack decides that Cody is the greatest writer in the world, though he'll never write a thing.
Cody brings Jack to Billie's apartment in the city. Jack and Billie "go for each other like two tons of bricks," so Cody leaves them alone.
Jack and Billie make love.
Jack ends up staying at Billie's place, sitting in the same chair and drinking for a week. He meets her son Elliot, whom he doesn't like.
Jack and Perry go to visit some "beautiful girls" who turn out to be under the age of ten. Jack is very out of it, and nearly incapable of carrying on conversation. The vast amounts of alcohol he has been consuming is starting to affect his mental and emotional states.
During his stay with Billie, many guys in the gang try to stop Jack from drinking. Finally, Ben Fagan takes Jack out or a walk, and Jack falls asleep in the park under his watchful eye.
Jack is disturbed at the death of Billie's goldfish; he wonders if it was his fault.
Jack and Billie make plans to marry and be together forever.
Jack calls Dave Wain and arranges for the two couples – Jack and Billie and Dave and Romana – to go out to Big Sur together. Dave agrees and drives down to brings them all to the cabin.
On the trip there, Jack is happy, but he has the sense that his elation is the start of a bad trip.
Jack and Billie have some issues at Big Sur: Jack doesn't want to sleep with her, and he realizes that he doesn't love her. Billie doesn't respond well and threatens to kill herself as well as her son, Elliot.
While watching her by the water, Jack titles the scene of Billie walking the beach "St. Carolyn by the Sea." He also imagines her as Ophelia, from Shakespeare's Hamlet.
As his madness gets worse, Jack finds himself unreasonably paranoid, especially with respect to his friends. He imagines that they're tying to kill him, drive him mad, or make him miserable. Even sex feels antagonistic to him. He can't bring himself drink the water from the river because he thinks someone put kerosene in it.
Through this period of alcohol induced madness, Jack continues drinking and refusing to eat.
While everyone else prepares dinner, Jack feels guilty about his own uselessness.
The scenery starts to shift in Jack's mind, and everything becomes sinister and terrifying.
That night Jack can't sleep anywhere; he resents Dave and Romana for taking the good sleeping spot down by the creek.
This night turns out to be the climax of Jack's delirium breakdown, toward which the novel's been building. Jack is tormented by paranoia, visions, and nightmares that conclude in a striking vision of the Cross.
Dawn doesn't alleviate the pain, and in the morning Jack begs Dave to let them leave early, instead of staying the whole week.
Finally, Jack passes out asleep on the porch. When he wakes up, he feels better. He imagines that he'll go back home to his mother, and the burial shrine of his dead cat, and "something good will come out of all things yet."