Montreal, late 1920s. Refusing to suffer the racist violence of thugs in his inner city, Joe Weider (Tyler Hoechlin
), the son of Polish Jewish emigrants, develops a passion for bodybuilding and the representation of the perfect human body. With his younger brother Ben (Aneurin Barnard
), the ambitious young man creates a bodybuilding magazine empire and begins building workout equipment, as well as designing training courses.
After moving to Los Angeles, Joe falls in love with pin-up queen Betty Brosmer (Julianne Hough), who shares his obsession with fitness and promoting healthy eating. In 1965, to compete with the Mr. Universe contest, which is run by an anti-Semite, Joe creates a new competition with Ben and Betty. Titled Mr. Olympia, the competition introduces a bodybuilding phenom to the world — Austrian Arnold Schwarzenegger (Calum Von Moger).