The detectives return to their territory in Herblingen, which Gabriel describes as the "Lugano of Northern Switzerland."
A debate about the correct tipping etiquette for coffee leads to questions about the economic value of their work.
An old radio is found at an illegal dump site. Gabriel begins a forensic investigation involving DNA and fingerprints.
The team deals with the difficulties of waste disposal near the border and the differences between Swiss and German trash.
A dead guinea pig wrapped in a newspaper is found in the forest. The question arises: how does one dispose of a pet correctly?
A trail of dog waste bags through Herblingen inspires Michel to come up with a new business idea.
While Oli tries to start smoking, the detectives find ultrasound images in the trash, leading to dark suspicions.
A sample from an underground container leads the detectives to the local post office and their surveillance cameras.
The season finale: Gabriel reflects on his career while a fox – or nature itself – is identified as the ultimate litterer.