In a bustling city, health inspector Paul Harris uncovers a shocking and dangerous secret when a large shipment of contaminated grain is found infested with oversized rats. Despite efforts to get rid of the tainted food, the monstrous rodents escape, carving a path of destruction and terror through the urban landscape. Harris, alongside his colleague Kelly Leonard, struggles to convince the authorities of the severity of the threat. The rats, now growing bolder and hungrier by the day, pose a greater risk to the unsuspecting populace.

As the rats continue their rampage, targeting homes, businesses, and even schools, the situation grows increasingly dire. The local exterminator George Foskins tries desperately to contain the invasion with limited success. Harris and Leonard work tirelessly to find a solution before the infestation spirals completely out of control. As panic sets in among the city’s residents, Harris must navigate bureaucratic hurdles and personal fears to save the city from this unprecedented menace.