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.

With a husband and two children Kate Mayer is unsatisfied with her life. To change she leaves her husband and finds a job at the offices of realtor McNally 'Mac' Hays. Having become invigorated by her new life she also finds herself conflicted as she finds herself having warm feelings for Mac.