In Manhattan, when a client is bitten by a rat in the dressing room of the Garsons Department Store and contracts Weil's disease, the manager Susan Costello is assigned to hire and give all the necessary support to the best exterminator in New York, Jack Carver. The efficient Jack and his assistant Ty find a colony of mutant rats and try to convince the health department administrator and former partner of Jack, Ray Jarrett, how serious the infestation is. But the politician Ray is interested in covering the problem to protect economical interests of powerful groups.