The series takes place in a world plagued by Shocker, a mysterious world-wide terrorist organization formed by remaining members of the Nazis. To further its plans for world domination, Shocker recruited its agents through kidnapping, turning their victims into mutant cyborgs and, ultimately, brainwashing them. However, one victim named Takeshi Hongo escaped just before the final brainwashing. With his sanity and moral conscience intact, Hongo battled Shocker's minions as the grasshopper-themed altered human superhero Kamen Rider.