The Great Gatsby is a story told by Nick Carraway, who was once Gatsby's neighbor, and he tells the story sometime after 1922, when the incidents that fill the book take place. As the story opens, Nick has just moved from the Midwest to West Egg, Long Island, seeking his fortune as a bond salesman. Shortly after his arrival, Nick travels across the Sound to the more fashionable East Egg to visit his cousin Daisy Buchanan and her husband, Tom, a hulking, imposing man whom Nick had known in college. There he meets professional golfer Jordan Baker. The Buchanans and Jordan Baker live privileged lives, contrasting sharply in sensibility and luxury with Nick's more modest and grounded lifestyle. When Nick returns home that evening, he notices his neighbor, Gatsby, mysteriously standing in the dark and stretching his arms toward the water, and a solitary green light across the Sound.
One day, Nick is invited to accompany Tom, a blatant adulterer, to meet his mistress, Myrtle Wilson, a middle-class woman whose husband runs a modest garage and gas station in the valley of ashes, a desolate and run-down section of town that marks the convergence of the city and the suburbs. After the group meets and journeys into the city, Myrtle phones friends to come over and they all spend the afternoon drinking at Myrtle and Tom's apartment. The afternoon is filled with drunken behavior and ends ominously with Myrtle and Tom fighting over Daisy, his wife. Drunkenness turns to rage and Tom, in one deft movement, breaks Myrtle's nose.
Following the description of this incident, Nick turns his attention to his mysterious neighbor, who hosts weekly parties for the rich and fashionable. Upon Gatsby's invitation (which is noteworthy because rarely is anyone ever invited to Gatsby's parties — they just show up, knowing they will not be turned away), Nick attends one of the extravagant gatherings. There, he bumps into Jordan Baker, as well as Gatsby himself. Gatsby, it turns out, is a gracious host, but yet remains apart from his guest — an observer more than a participant — as if he is seeking something. As the party winds down, Gatsby takes Jordan aside to speak privately. Although the reader isn't specifically told what they discuss, Jordan is greatly amazed by what she's learned.
As the summer unfolds, Gatsby and Nick become friends and Jordan and Nick begin to see each other on a regular basis, despite Nick's conviction that she is notoriously dishonest (which offends his sensibilities because he is "one of the few honest people" he has ever met). Nick and Gatsby journey into the city one day and there Nick meets Meyer Wolfshiem, one of Gatsby's associates and Gatsby's link to organized crime. On that same day, while having tea with Jordan Baker, Nick learns the amazing story that Gatsby told her the night of his party. Gatsby, it appears, is in love with Daisy Buchanan. They met years earlier when he was in the army but could not be together because he did not yet have the means to support her. In the intervening years, Gatsby made his fortune, all with the goal of winning Daisy back. He bought his house so that he would be across the Sound from her and hosted the elaborate parties in the hopes that she would notice. It has come time for Gatsby to meet Daisy again, face-to-face, and so, through the intermediary of Jordan Baker, Gatsby asks Nick to invite Daisy to his little house where Gatsby will show up unannounced.
The day of the meeting arrives. Nick's house is perfectly prepared, due largely to the generosity of the hopeless romantic Gatsby, who wants every detail to be perfect for his reunion with his lost love. When the former lovers meet, their reunion is slightly nervous, but shortly, the two are once again comfortable with each other, leaving Nick to feel an outsider in the warmth the two people radiate. As the afternoon progresses, the three move the party from Nick's house to Gatsby's, where he takes special delight in showing Daisy his meticulously decorated house and his impressive array of belongings, as if demonstrating in a very tangible way just how far out of poverty he has traveled.
At this point, Nick again lapses into memory, relating the story of Jay Gatsby. Born James Gatz to "shiftless and unsuccessful farm people," Gatsby changed his name at seventeen, about the same time he met Dan Cody. Cody would become Gatsby's mentor, taking him on in "a vague personal capacity" for five years as he went three times around the Continent. By the time of Cody's death, Gatsby had grown into manhood and had defined the man he would become. Never again would he acknowledge his meager past; from that point on, armed with a fabricated family history, he was Jay Gatsby, entrepreneur.
Moving back to the present, we discover that Daisy and Tom will attend one of Gatsby's parties. Tom, of course, spends his time chasing women, while Daisy and Gatsby sneak over to Nick's yard for a moment's privacy while Nick, accomplice in the affair, keeps guard. After the Buchanans leave, Gatsby tells Nick of his secret desire: to recapture the past. Gatsby, the idealistic dreamer, firmly believes the past can be recaptured in its entirety. Gatsby then goes on to tell what it is about his past with Daisy that has made such an impact on him.
As the summer unfolds, Gatsby and Daisy's affair begins to grow and they see each other regularly. On one fateful day, the hottest and most unbearable of the summer, Gatsby and Nick journey to East Egg to have lunch with the Buchanans and Jordan Baker. Oppressed by the heat, Daisy suggests they take solace in a trip to the city. No longer hiding her love for Gatsby, Daisy pays him special attention and Tom deftly picks up on what's going on. As the party prepares to leave for the city, Tom fetches a bottle of whiskey. Tom, Nick, and Jordan drive in Gatsby's car, while Gatsby and Daisy drive Tom's coupe. Low on gas, Tom stops Gatsby's car at Wilson's gas station, where he sees that Wilson is not well. Like Tom, who has just learned of Daisy's affair, Wilson has just learned of Myrtle's secret life — although he does not know who the man is — and it has made him physically sick. Wilson announces his plans to take Myrtle out West, much to Tom's dismay. Tom has lost a wife and a mistress all in a matter of an hour. Absorbed in his own fears, Tom hastily drives into the city.
The group ends up at the Plaza hotel, where they continue drinking, moving the day closer and closer to its tragic end. Tom, always a hot-head, begins to badger Gatsby, questioning him as to his intentions with Daisy. Decidedly tactless and confrontational, Tom keeps harping on Gatsby until the truth comes out: Gatsby wants Daisy to admit she's never loved Tom but that, instead, she has always loved him. When Daisy is unable to do this, Gatsby declares that Daisy is going to leave Tom. Tom, though, understands Daisy far better than Gatsby does and knows she won't leave him: His wealth and power, matured through generations of privilege, will triumph over Gatsby's newly found wealth. In a gesture of authority, Tom orders Daisy and Gatsby to head home in Gatsby's car. Tom, Nick, and Jordan follow.
As Tom's car nears Wilson's garage, they can all see that some sort of accident has occurred. Pulling over to investigate, they learn that Myrtle Wilson, Tom's mistress, has been hit and killed by a passing car that never bothered to stop, and it appears to have been Gatsby's car. Tom, Jordan, and Nick continue home to East Egg. Nick, now disgusted by the morality and behavior of the people with whom he has been on friendly terms, meets Gatsby outside of the Buchanans' house where he is keeping watch for Daisy. With a few well-chosen questions, Nick learns that Daisy, not Gatsby, was driving the car, although Gatsby confesses he will take all the blame. Nick, greatly agitated by all that he has experienced during the day, continues home, but an overarching feeling of dread haunts him.
Nearing dawn the next morning, Nick goes to Gatsby's house. While the two men turn the house upside down looking for cigarettes, Gatsby tells Nick more about how he became the man he is and how Daisy figured into his life. Later that morning, while at work, Nick is unable to concentrate. He receives a phone call from Jordan Baker, but is quick to end the discussion — and thereby the friendship. He plans to take an early train home and check on Gatsby.
The action then switches back to Wilson who, distraught over his wife's death, sneaks out and goes looking for the driver who killed Myrtle. Nick retraces Wilson's journey, which placed him, by early afternoon, at Gatsby's house. Wilson murders Gatsby and then turns the gun on himself.
After Gatsby's death, Nick is left to help make arrangements for his burial. What is most perplexing, though, is that no one seems overly concerned with Gatsby's death. Daisy and Tom mysteriously leave on a trip and all the people who so eagerly attended his parties, drinking his liquor and eating his food, refuse to become involved. Even Meyer Wolfshiem, Gatsby's business partner, refuses to publicly mourn his friend's death. A telegram from Henry C. Gatz, Gatsby's father, indicates he will be coming from Minnesota to bury his son. Gatsby's funeral boasts only Nick, Henry Gatz, a few servants, the postman, and the minister at the graveside. Despite all his popularity during his lifetime, in his death, Gatsby is completely forgotten.
Nick, completely disillusioned with what he has experienced in the East, prepares to head back to the Midwest. Before leaving, he sees Tom Buchanan one last time. When Tom notices him and questions him as to why he didn't want to shake hands, Nick curtly offers "You know what I think of you." Their discussion reveals that Tom was the impetus behind Gatsby's death. When Wilson came to his house, he told Wilson that Gatsby owned the car that killed Myrtle. In Tom's mind, he had helped justice along. Nick, disgusted by the carelessness and cruel nature of Tom, Daisy, and those like them, leaves Tom, proud of his own integrity.
On the last night before leaving, Nick goes to Gatsby's mansion, then to the shore where Gatsby once stood, arms outstretched toward the green light. The novel ends prophetically, with Nick noting how we are all a little like Gatsby, boats moving up a river, going forward but continually feeling the pull of the past.