Rider Scout Shotaro has discovered Shocker mutants entombed in a lakeside cave. When he arrives, the mutants are gone, but Kazami Shiro is ambushed by Destron's powerful Quoit-Beetle. Destron plots to destroy the whole of Japan by resurrecting former Shocker Commandants Colonel Zol, Doctor Death, Ambassador Hell and General Black, using a newly developed toxic gas called Girard Gamma. Suddenly, V3 is attacked by the revived Shocker mutants, led by Quit-Beetle!

Trapped by the five commandants Kazami Shiro falls into an unbreakable cell. Tachibana Tobei, in a bid to rescue Shiro, poses as a scientist who has developed an antidote to the nerve gas, and is abducted. Meanwhile, Shiro turns the table on Ambassador Hell and takes him hostage in order to escape. But, he must infiltrate the outpost once more in to rescue Tachibana and Junko. Can V3 save Japan, as well as his friends, from certain death?