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.

A young woman marries a fascinating widower only to discover that she lives in the shadow of his former deceased wife, Rebecca. The young wife must also deal with the jealous, obsessed housekeeper, who will not accept her as the mistress of the house.

A mysterious, man-sized monster kills a fisherman at sea. A Biologist and a Federal Agent discover a man's body, washed up on the beach and covered with radiation burns.