Christmas time in the Vorderpfalz. Just during the Christmas party of the Schifferstadt Criminal Investigation Department, a disaster alarm is triggered: the narrow dike near Altrip has been damaged by an explosion. Parts of the huge campsite "Auf der Au," located directly on the Rhine, are flooded. Fortunately, there are only a few injuries, as hardly anyone is on the site just before Christmas. But then a blackmail letter with a demand in the millions announces further attacks. And when Commissioner Reiner Palzki is also notified of a dead ship captain on the premises of the Rheingüter shipping company in the Ludwigshafen Kaiserwörth harbor, the situation threatens to escalate. A race against time begins...