A physicist named Tetsuo Okita discovers a new mineral called "Satanium," which is more powerful than uranium and emits destructive effects to anyone exposed to it. However, Destron abducts Okita in hopes of finding the source of Satanium and collecting more of it to expedite their run for global domination. Kamen Rider V3 must act fast in rescuing Professor Okita and preventing Destron from collecting more of the deadly mineral.