Ratten 2 - Sie kommen wieder! (2004)

Three years after the rat epidemic in Frankfurt, Stuffz, Honsa, and Katrin travel to their friend Axel’s wedding. Shortly after they arrive, Axel’s assistant is found dead—supposedly killed by a wild dog. But Katrin is certain that it wasn’t a dog that killed the young woman; it was rats. When another body is found in the sewer system soon afterward, Katrin’s suspicion becomes a certainty: the rats are attacking again, and it is once again their job to stop the invasion of the small rodents. Professor Matthäi realizes that some of his experimental rats have escaped and multiplied. When he goes to catch a rat in the old rendering plant, he is attacked and killed by a whole swarm of rats. Dabrock and his friends find Matthäi’s body and are attacked as well. While fleeing, Dabrock falls to his death, while the others manage to escape. Stuffz-Hubert and Svenja realize that Matthäi had manipulated the rats’ genes so that they would die in winter, thereby ensuring that a rat plague could never occur again. Some rats would always survive and reproduce. However, the rats become aggressive as the temperature approaches the fatal level. To end the rat plague, they lure the rats into an abandoned factory, and Stuffz-Hubert blows up nitrogen cylinders, causing the rats to freeze to death.