Zasu Pitts and Thelma Todd are working their way through college by selling magazine subscriptions. Finding little success going door-to-door, the pair decide to use their charms to sell to men at their places of work.

Gaira, a humanoid sea beast spawned from the discarded cells of Frankenstein’s monster, attacks the shores of Tokyo. While the Japanese military prepares to take action, Gaira’s Gargantua brother, Sanda, descends from the mountains to defend his kin. A battle between good and evil ensues, leaving brothers divided and a city in ruins.