A gruesome discovery on the beautiful Rhine in Cologne poses a mystery: young activist Luise is found dead, washed up on the riverbank. Inspector Clara and her colleague Hans begin investigating the murder and become entangled in a web of environmental pollution, online threats and encrypted company data. They fish in murky waters until they finally uncover explosive information about a large regional chemical company. Water evokes emotions. For the Cologne soul in particular, it is more than just a biological elixir necessary for survival: numerous myths and stories lie slumbering at the bottom of the Rhine, and no other German body of water has been sung about as much as the Rhine. The title of the play is taken from a famous line in a song by the Cologne band Bläck Fööss. But how clean is the Rhine? Peppered with Rhineland songs, Calle Fuhr's DAT WASSER VUN KÖLLE ES JOT tells a Cologne crime story that reveals uncomfortable facts about the water quality of the Rhine: explosive research findings by the investigative media company CORRECTIV are brought to the stage.