Marco Fogg recalls the events of the summer of 1969, when humans first stepped foot on the moon and Marco radically transformed his own life. Marco, an orphan, moves to New York to study at Columbia. He brings with him his Uncle Victor’s library. Victor, a clarinetist and bachelor, raises Marco in Chicago after the death of Marco’s mother, Emily. When Marco moves out Victor decides to tour with his band, the Moon Men, and gives Marco all his worldly possessions. Marco distinguishes himself in college with his bohemian lifestyle and moves into an apartment near the campus.
The following autumn, Victor dies of a heart attack in Boise, Idaho. Marco retrieves his body and buries him in Chicago, but he begins to spiral upon his return from New York. Even though his inheritance is running out, Marco refuses to find work or scholarships, and he instead invents an elaborate routine to stretch out his money and food for as long as possible. He hides from his friends and becomes dangerously underweight. Eventually, in despair, Marco visits his friend Zimmer for a loan, only to find a new tenant living in Zimmer’s apartment and meet the tenant’s charming guest, a Chinese dance student named Kitty Wu.
Soon after graduating, Marco is evicted and drafted. He wanders through Manhattan by day and sleeps in Central Park, closely following baseball news and scrounging together just enough food to survive. Marco falls ill and nearly dies, but he is rescued just in time by Kitty and Zimmer—after meeting Marco, Kitty grew concerned and tracked down Zimmer, and they have been looking for Marco for weeks. Zimmer takes Marco in and helps him recover. Thanks to his weakened state, Marco does not pass his army physical and avoids the draft. Zimmer tells him about Kitty’s life: the daughter of a Chinese general, she too is an orphan of sorts, adrift and alone in New York. Marco takes on translation work for Zimmer to repay his kindness and strikes up an affair with Kitty. Looking for more work and independence, he accepts a job as a live-in companion for an older, disabled man.
Marco’s new employee, Thomas Effing, is blind, wheelchair-bound, and very rich. Effing is also mean-spirited, aggressive, and possibly a pathological liar—he claims to be clairvoyant, too. Still, Marco settles in with Effing and his live-in nurse, Rita Hume, and spends his days reading to Effing and taking him for walks. Effing previously lived in Paris with Marco’s predecessor, Pavel Shum, but is otherwise a complete shut-in. After a few months, Effing tells Marco it is time to start working on his own obituary: he claims to know exactly when he will die and wants Marco to record his life story. Effing explains that his real name is Julian Barber, and he was an up-and-coming American painter presumed dead in 1917.
Over several weeks, Effing fills in the story. He explains how he left the turn-of-the-century New York arts scene and his unhappy marriage to travel to Utah and paint Western landscapes. Traveling west with a family friend named Teddy Byrne, Effing hires a man named Scoresby to guide them through the desert. Scoresby comes to resent the two New Yorkers and eventually betrays them, leading them into rough territory that causes Byrne to fall off his horse and eventually die of his injuries. Scoresby then abandons Effing, who wanders the desert alone until he finds a furnished and well-stocked cave with a dead hermit in it—recently shot in the face by an unknown person. Effing takes up residence in the cave, painting and journaling with the last of his materials. After several months, Effing is visited by the Native American outlaw George Ugly Mouth, who mistakes him for the hermit. Through their conversation Effing discovers that the hermit was killed by the train robber Gresham Brothers, who are on their way back to the cave after a successful heist. Instead of leaving, he waits for their arrival.
When the Gresham Brothers return, Effing catches them by surprise, kills them, and takes their enormous score—more than $20,000—for himself. Effing continues west to San Francisco and starts a new life under the name Thomas Effing, but he lives in fear of discovery until one night he falls down a San Francisco hill, hits a lamppost, and becomes paralyzed from the waist down. Effing now truly feels like a new man and sets out for Paris, where he will live until 1939.
In the present, Marco transcribes and rewrites Effing’s story for publication—and to send to Effing’s estranged son, a morbidly obese history professor named Solomon Barber. Effing then recruits Marco into a scheme to “repay” his debt and give away $20,000 in cash to strangers on the street. Effing is overjoyed to hand out money but insists on going out in the rain with a (unbeknownst to Marco) broken umbrella and catches pneumonia, eventually dying on the exact day he said that he would. Marco helps settle Effing’s affairs and moves in with Kitty; they use Effing’s parting gift of $7,000 to rent their own apartment.
Marco finally hears back from Barber, who visits New York to talk to him. Barber is very interested in Marco’s own life story. As Marco will learn later, Barber is in fact Marco’s father from a brief affair with Barber’s former student, Emily. The scandal of that affair and the heartbreak of losing Emily led Barber to live an isolated life ever since, and he moves from college to college every few years. In their first meetings, however, Barber just tells Marco about his own life, explaining how he was raised by servants because of his mother’s mental illness, showing Marco his teenage novel about his missing father, and telling him about how he insisted that his family’s maid inherit their house on Long Island.
Barber moves to New York shortly before Marco and Kitty break up. Kitty is pregnant but insists on an abortion over Marco’s strenuous objections. Marco, distraught, moves in with Barber before agreeing to join him in a search for Effing’s cave in Utah. Driving west, they stop in Chicago to visit Emily and Victor’s graves, where Barber bursts into tears. Marco is disturbed by the sudden realization that Barber is his father, but as they argue, Barber falls into an open grave and breaks his back. The two reconcile and share the full, true story with each other while Barber is in the hospital, but he soon takes a downturn and dies.
Marco buries Barber in the plot reserved for himself and calls Kitty and asks her to take him back. When she gently refuses, he sets out west in search of the cave. As Marco learns in Utah, however, the cave is gone forever, flooded by an artificial lake. Marco goes boating on the lake only to find his car—and in it, the last of Effing’s fortune, which he has inherited from Barber—stolen. Unsure what to do, Marco sets off on foot, following Effing’s footsteps and walking all the way to the seashore in California.