The nefarious Reptoids, defeated and relinquished to hidden outskirts away from the Northern Kingdom, abscond with the human race's final hope for survival—the last of their children. Motro convinces the city's elders to sacrifice themselves to reveal the Reptoids' location so the children may still be rescued, but they're met with a horrifying discovery. Motro, with great warriors and a squadron of tri-tankerbeasts at his side, must decide what it means to save humanity when faced with extinction or a grisly new future.