The body of a homeless man is found in Cologne not in the Dark Ages, but in the year 2000, where an autopsy reveals that he died of the plague. Doctor Martin Brügger sets out to find the cause and discovers masses of dead rats in the sewers. The population of the Rhine metropolis is in danger - but the authorities do not want to cause panic and keep the case a secret.

The film is based on the events surrounding the Lengede mining accident in 1963.