College student and aspiring motocross racer Takeshi Hongo is abducted by evil organization known as "Shocker" and converted into a cyborg warrior to do their bidding. But before the Shocker can brainwash him, an explosion occurs in the laboratory and Hongo escapes. Using his new powers, Hongo becomes Kamen Rider and wages a battle to keep mankind safe from Shocker. During Kamen Rider's battles with Shocker, photographer Hayato Ichimonji is abducted in Mexico by the organization and converted into a cyborg. Unfortunately for them, Kamen Rider interferes with the operation and Ichimonji becomes Kamen Rider 2, Shocker's newest enemy.