Julia, a young woman on the fringe of society, lives off of petty tricks and has a devouring, almost animal-like passion for motorcycling. One summer day, she meets a group of bikers who are adept at cross-bitume, a trend that consists of riding at full speed and performing acrobatic tricks with one's machine, most of the time without a helmet. The heroine will infiltrate this clandestine circle, made up mainly of young men, before an accident weakens her position within the gang.