In 2045, much of Earth’s population centers have become slum-like cities. To escape their desolation, people engage in the virtual reality world of the OASIS (Ontologically Anthropocentric Sensory Immersive Simulation), where they can engage in numerous activities for work, education, and entertainment. Users have discovered “Anorak’s Quest” hidden within OASIS, a game programmed by the late James Halliday, the creator of OASIS. The first to find the Easter egg within Anorak’s Quest is promised full ownership of OASIS among other gifts. This has attracted a number of Gunters (“egg hunters”) to play the game. Innovative Online Industries (IOI), a video game conglomerate and manufacturer of most of the virtual reality equipment used to access the OASIS, also seeks ownership of the virtual reality world, and its CEO, Nolan Sorrento, has amassed an army of debt-indentured players, known as Sixers (due to their six-digit identification), to seek the prize. However, to date, no one has been able to complete the first quest, finishing a vehicle race across an ever-shifting dangerous cityscape.
Wade Watts, an 18-year-old Gunter who is an orphan, lives in a Columbus, Ohio slum with his aunt. In the OASIS, Wade goes by his avatar Parzival, and has partnered with Aech, a male avatar that serves as a virtual mechanic. He later befriends well-known player Art3mis after saving her from being “zeroed out”, which would reset their avatar’s character progression. Wade decides to study the virtual OASIS library to learn about Halliday’s personal life in hopes of finding a hint to finish the race. Wade learns that Halliday felt regret when he had to accept the resignation of his partner, Ogden Morrow, over a personal falling-out, with Halliday musing, “Why can’t we go backwards for once? Backwards really fast, as fast as we can – really put the pedal to the metal.” At the next race, Wade reverses from the start line, finding a hidden, safe path to the finish line of the race. He gains the first of three keys and a clue to the next quest. Aech, Art3mis, as well as players Daito and Sho follow Wade to finish the quest, and the five appear atop the global scoreboards, becoming known as the “High Five”.
IOI takes keen interest in them, desiring to learn their real-life identities. Bounty hunter i-R0k overhears Wade tell Art3mis his real name, disclosing it to Sorrento, who approaches Wade in an attempt to convince him to join IOI to solve Anorak’s Quest, but Wade refuses. In retaliation, Sorrento has his assistant F’Nale Zandor attack Wade’s slum, killing Wade’s aunt and her boyfriend. Wade is rescued by Art3mis’ real-life friends and is taken to a Gunter hideout in Columbus, where he meets Art3mis’ player, Samantha Cook. The two discover that Halliday had once dated Kira, who later became Morrow’s wife, and was the source of their falling out. In the virtual OASIS archives, Wade wins a bet with its Curator regarding whether Kira’s memory remains anywhere within the archives, and the Curator rewards him with a 25-cent coin and grants him access to Halliday’s memories of Kira, which turn out to be the entrance to the second quest. By surviving a recreation of The Shining while searching for Kira, the High Five team each gain the second key and the clue that the last quest is in Castle Anorak on Planet Doom.
Zandor discovers the Gunter hideout and kidnaps Samantha. Meanwhile, Wade is rescued by the real-life players of Aech, Daito and Sho, who have taken to hiding in Aech’s van. In the OASIS, they learn that IOI has erected a field blocking access to the castle, maintained by IOI and the Sixers, including an enslaved Samantha. Wade sends a message to all OASIS players about IOI’s activities, and convinces many to join their side to fight against IOI and the Sixers. With Aech, Daito, and Sho leading the army of players, Samantha is able to use the distraction to shut down the field and allow Wade access inside Castle Anorak. Wade finds that several Sixers have found the Atari room, trying to determine which Atari 2600 game was Halliday’s favorite; choosing and completing the wrong one leads to being zeroed out. Sorrento and Wade recognize the right game as Adventure, but even successfully completing it causes the playing Sixer to be zeroed out.
With Wade now alone in the Atari room, Sorrento desperately decides to activate the Cataclyst, which zeroes out all players on Planet Doom. However, the Curator’s coin is revealed to be an extra life, which allows Wade’s avatar to survive, and he continues the quest. Wade deduces that the goal is not to win Adventure but to find its own Easter egg. Upon doing so, he is given the last key. Wade uses the keys to open a gate in the castle, where he is congratulated by Anorak. Anorak presents him with a contract to sign, but Wade recognizes it as the one Morrow had to sign on his termination, and turns it down. The avatar of Anorak transforms into a projection of Halliday, who reveals that this was a final test, one that centered around his biggest regret in his life. Halliday offers Wade the opportunity to wipe out the OASIS with the Big Red Button if he feels that is for the best, and otherwise awards him with the Golden Egg, transferring control of OASIS to Wade. Wade questions whether the projection of Halliday is actually him in OASIS and whether he is really dead.
Sorrento and Zandor are arrested, and IOI is heavily restructured as a company, with the indentured servitude division removed. Wade opts to share control of OASIS with the other High Five. Morrow offers to help consult on a salary of 25 cents, while revealing he had been the Curator within OASIS. The High Five decide to have OASIS shut down twice a week in order to force people into spending more time in the real world, while Wade and Samantha start a romantic relationship and move in together in an apartment.