The film begins with main character Michael 'Micky' Clark (Darryl Hickman) tuning his late-1920s/early-1930s era Ford roadster into a hot rod with his friend Todd (Robert Arthur), based on the advice of Michael's older brother Jeff, who learned about engines while serving as a navy pilot during WW2. Todd (who already has his own custom Ford hot rod) is critical of Michael for talking about his brother too much, but encouraging to Michael towards the idea of souping up his car. Meanwhile across town, Michael/Jeff's father John is on his way home in a brand new convertible when he witnesses a fatal car accident on the highway, caused by reckless driving. Arriving home with the car to show his family (and friends who happen to be at the house), Todd comments with enthusiasm about how the car's speedometer goes up to 120MPH, which in turn causes John to give a lecture to the teenage boys about the dangers of street racing, and warns his son Michael to be safe behind the wheel. Despite the lecture however, John himself has his own reckless driving habits (which he refuses to admit to). John's "need for speed" is put on full display to the family when he gives them a ride in the new car. Later on, Michael's plans of being a safe driver change when girlfriend Peggy (Sue England), his friend Todd, & Todd's girlfriend Rusty (Terry Moore) all make fun of Michael for wanting to be cautious behind the wheel. Upset by this, Michael decides to participate in a street race with Todd. Despite the police intervening in the race, Michael does not seem phased to give up reckless driving, and later on takes Todd for a ride in his father's new convertible, driving recklessly through the streets & evading the police.
Despite Michael & Todd's luck in the these last two encounters with police as well as the death of a fellow racer, they continue driving recklessly, in part because of the encouragement they receive from their girlfriends, who like it when they ride fast. However, Michael and Todd eventually push their luck to the point of fatal consequences. Throughout the film, county judges, police investigators, and newsmen continuously warn about the dangers of street racing. In the final scene in the film, Michael's father John still possesses hotheaded driving habits, though when he hears a police siren he appears to instantly cool down & loose his interest in driving fast & reckless.