Summary So-called "overbarrels" of hazardous waste keep floating in the Elbe. When little Henry (12) pulls one of these barrels onto land, the police are able to prevent something bad from happening at the last moment: In addition to other chemical substances, this barrel also contains a bottle of mercury, which forms a life-threatening neurotoxin when combined with water. As long as the background is not clear, swimming and fishing are prohibited on the Elbe: environmental alarm for the police. The investigation leads to Mila Ahlers' recycling center, which has fallen into financial difficulties, the shady gold prospector Mirko Bode and a closed pharmacy, where the supposed "artist" Freddy Bönisch is pursuing the implementation of a suspicious business idea. In the showdown, the police are able to prevent a mercury catastrophe in little Henry's play hiding place by a hair's breadth.

• Crime