It's the summer of 1962 in Modesto, California, and 4 friends - Steve (Ron Howard), Curt (Richard Dreyfus), John (Paul LeMat), and Terry "the Toad" (Charles Martin Smith) - are spending their last night together. Steve and Curt are to leave the next morning to go to college on the East coast. The four of them are at a local drive-in restaurant at the beginning of the evening. Steve, his girlfriend Laurie (Cindy Williams), and Curt are going to go to a dance, while John wants to cruise the streets in his yellow deuce coupe. Terry, who was given Steve's Chevy Impala to watch while he is gone, also wants to cruise the streets. The four stories intertwine, so I will recap them one at a time.
STEVE AND LAURIE'S STORY
Steve suggests to Laurie that they see other people while they are apart, which Laurie is against. She wants Steve to stay in town, even though he has said that he is eager to leave Modesto. Throughout the movie, Laurie tries to convince Steve to stay, but he refuses, which ultimately leads to them breaking up. A distraught Laurie is walking home when she is picked up by another cruiser, Bob Falfa (Harrison Ford). Bob is looking for John to race against him.
John pulls up to a car full of girls and asks if one of them wants to ride with him. One girl gets in his car, but John is horrified when he realizes that Carol (Mackenzie Phillips) is only 12 years old. At first, John tries to get her to get out, but she refuses. As the night wears on, John and Carol become friends. When he drops her off, she tells him that this was the best night of her life. As John returns to cruising, he meets up with John and Laurie, who challenges him to a race.
On the way to the dance with Steve and Laurie, Curt sees a blond in a white T-bird (Suzanne Somers) mouth "I love you" to him before pulling away. Throughout the night, Curt tries to catch up to the T-bird, but keeps missing her. His adventures include riding with a group of greasers called The Pharaohs, who welcome him into the group after pulling a prank on a couple of policemen (the famous scene of the police car's rear axle being pulled off). He goes to the local radio station and asks the DJ (Wolfman Jack) to read to message on the air for the blond. Early the next morning, a phone ringing wakes up Curt, and it's the blond. She tells him she will see him the next night, but he tells her he is leaving town and she hangs up. Curt then heads to the airport to leave.
Terry has picked up Debbie (Candy Clark) by pretending that Steve's car is really his. Their date ends abruptly when the car is stolen, but they eventually find it in a garage. Terry and a passing John fight the crooks and gets the car back. They return to the drive-in, where a waiting Steve wants the car back to find Laurie. It's then that Terry admits to Debbie that the car is not his and he only has a Vespa scooter. Debbie tells him that she likes motorcycles more than cars, and a scooter is close to a motorcycle.
The stories converge when John accepts Bob's challenge to a race at dawn. The race doesn't last long, as Bob quickly crashes his car. Steve, Terry, and John all run to the wreck, where Bob and Laurie emerge before it explodes. Laurie quickly embraces Steve and implores him not to leave her. Steve tells her that he has changed his mind and will go to a local college in Modesto. John tells Terry that he was losing the race when Bob crashed and not to tell anyone. They all then go to the airport to say goodbye to Curt. As his plane takes off, Curt looks out the window and sees the T-bird following him.
Title cards at the very end say that John was killed by a drunk driver in December of 1964, Terry was declared missing in action in Vietnam in December of 1965, Steve became an insurance agent in Modesto, and Curt became a writer in Canada.