Adam Larson and four other college students; Harold, Wesley, Donna and Levitas; are invited to compete in “The Great All-Nighter,” an event sponsored by Game Master Leon. Each has been selected to be a team captain, form a team, and solve a series of clues around the city until one team wins. Adam’s coworker, Laura, encourages him to have fun and play, while Harold’s father insists that his son participate after hearing about the game from Adam’s father. Elsewhere, Wesley recruits his debate team, who are eager for revenge, having been bullied by the football team. Football player Levitas eagerly drafts his fellow athletes, while Donna recruits her sorority sisters to avenge a pledge party that the football players ruined. At the game’s start on Friday night, all the teams receive the first clue: “See the stars.” The different interpretations scatter the green team to the Hollywood Wax Museum, the red team goes to a disco, the white team visits Hollywood Boulevard’s “Walk of Fame,” and the yellow team acquires a map of star homes. Harold’s father has bought him a state-of-the-art van equipped with a built-in computer, and it now directs Harold to Griffith Park Observatory. At Game Control, Leon’s landlady Mrs. Grimhaus threatens eviction if she hears one more complaint about the noise. Later, several teams head for the observatory after realizing they have picked the wrong destination. Marvin, from Adam’s yellow team, sets the observatory’s telescope coordinates to the clue’s numbers. A message appears on a digital outdoor billboard that says, “Find the 8800 keys.” Suddenly, Levitas’ green team appears, and tells the yellow team to get lost. Before Adam and his team leaves, he quietly resets the telescope’s coordinates. After Harold’s computer deciphers the next clue, his blue team drives to the Los Angeles piano museum. Before entering the museum, Harold hides his bag of marshmallows in the computer console before his girl friend, Lucille, sees him cheating on his diet. On the way, Adam sees his younger brother Scott at a bus stop bound for San Francisco and orders Scott to join the game. At the museum, Lucille spots music titled “Leon’s Theme,” scrawled on the front of a tabletop piano. However, Harold is unable to access the clue because the marshmallows have ruined the computer’s circuitry. In the museum, football player Armpit plays the notes in the clue and recognizes the music as the Pabst Blue Ribbon Beer jingle. He blurts out his discovery and all the teams, except Harold’s, race to the Pabst Brewery. On the way, red teammates, twins Patty and Lulu, are distracted by a street carnival. At the brewery, the yellow and green teams take the guided tour, while red team captain Donna and teammate Berle search for the twins. During the tour, the yellow team is kicked out when underage Scott tries to drink a beer. At first, Adam blames Scott for ruining the game but then he and his teammates see a new clue in the brewery warehouse, which reads “Mr. Carson’s obese male child.” The yellow team then races to Johnny’s Fat Boy burger restaurant. Soon, Harold follows the yellow team’s car to Johnny’s, while Donna and Berle collect Patty and Lulu. At Johnny’s parking lot, Harold and his team deflate the yellow team’s car tires and siphon off most of the gas. Inside, the clue on the blackboard reads, “Look between the two giant melons!” Although the teams eat slices of watermelon and cantaloupe, nothing turns up until the big-busted waitress breaks a dish and everyone scrambles for the necklace dangling from her neck. The necklace’s letters spell “Hug me,” leaving everyone puzzled, but when the yellow team rearranges the letters to read “Huge M,” they decide their next destination is Miniature Golfworld, whose signage contains a giant “M”. However, the yellow team is delayed by their sabotaged car. At the mini golf course, Harold cheats, ordering his team to go to the eighteenth hole instead of playing an entire round. In the green team car, Blaylak becomes sick because he dove into a vat of beer while at the brewery. The team fortuitously stops at the mini golf parking lot, and sees Harold’s van. Wesley’s white team has their ball thrown in the water by the green team, who finds the next clue “Look at xylophones initially (530 AM).” The initials of the first three words, L – A – X, represent Los Angeles International Airport and off they go. The white team is the first to set their radios to the airport information station, 530 AM, whereupon Leon’s voice directs them to terminal 3. There, Hare Krishnas insist that Wesley take a handbill, which contains the next clue, but Wesley discards it. When Harold elbows a pushy Krishna, fliers scatter and the next clue is revealed: “His Holiness says: You’re off your rocker if you don’t look inside the locker.” Each team finds a wrapped present containing three Polaroid images and a rubber ball. When all the items are assembled correctly, the clue reads: “Pinball City.” At the pinball arcade, a Madam Leona fortuneteller instructs the yellow team to win a specific video game for the next clue. Laura convinces Adam to let Scott play the game after the others strike out, and Leon’s videotaped message tells them the game’s finish line is somewhere in the Bonaventure Hotel. Given that Adam barely acknowledges Scott’s help, the younger brother runs away. At the arcade, the green and red teams fight to prevent each other from winning. Meanwhile, Adam believes his brother has sabotaged the game and heads for the Bonaventure, while Laura, Marvin and Flynch search for Scott. When Scott spies Harold’s van, he says he will provide the blue team with the next clue. However, Scott backpedals, so Harold threatens him to get the information and then dumps Scott out of the van. Soon, Adam has a change of heart and returns to finds Scott. At the arcade, as the fight winds down, the green team destroys the video game screen so that the white team cannot access the clue. As the green team leaves, they accidentally back their car into the red team truck, sending it careening into the L.A. River. However, the white team reluctantly provides the red team with a scooter for transportation. At the Bonaventure hotel, Leon has reserved a room where he waits for a winner. The teams scatter throughout the hotel searching for the final clue. When Leon pages Mr. Game Players, all teams run to the hotel phones. Leon says, “look at the pool area and I mean this expressly.” Up in the Game Control room, Mrs. Grimhaus calls security to tell them of Leon’s whereabouts. Adam’s yellow team takes the express elevator to the hotel’s rooftop restaurant as the blue team follows in a separate elevator, while the red, green and white teams throw each other in the pool. As the two elevators speed upward, the message “Room 2704” appears on an adjacent rooftop. When the yellow team switches to the correct elevator, Harold retaliates by damaging the hotel’s elevator mechanism. The yellow team and security are trapped in separate elevators while Harold’s team climbs the stairs. Marvin restarts the elevator using the wire from Scott’s bite plate, while the blue team begins to tire. Still, both the yellow and blue teams arrive simultaneously at the twenty-seventh floor. Harold grabs a fire hose from the wall, but Adam opens the security-filled elevator. As Harold sprays the security guards, they surround and capture the blue team. Leon and his entourage declare the yellow team the winners with a big banquet for all the contestants. Harold breaks free from security and begins gorging on the food. When Lucille tries to stop his eating, he pushes her into a nearby fountain. Nearby, Adam kisses Laura.