Ben, the leader of a group of intelligent rats, is no longer under the command of his wise young ward, Willard. Ben takes revenge by savaging Willard to death. Ben, with its innate intelligence, can lead the rats to wreak havoc on supermarkets and candy stores, killing humans who attempt to eradicate them. It even understands human language and gets along well with kind-hearted individuals. Ben forms a close friendship with Danny, a young boy suffering from heart disease. They often play games together and cuddle up at night. However, humans are not tolerant of their presence. The detective responsible for eradicating the rats eventually discovers their hiding place, leading to a battle between man and rat.