A summer of the century in Basel – but no vacation for Inspector Hunkeler. Instead of spending time with his partner Hedwig in Alsace, he has to take on a murky case: his family doctor, a liberal politician well known in the city, has been found murdered in her practice. A few drug addicts who had been supplied with methadone by her come under suspicion. But Hunkeler's instinct for the depths of the human psyche leads him unerringly down a different path.

Alicia Keys performs at the Baloise Session festival in Basel, Switzerland on 2 November 2017.

Two dead with their earlobes slashed. Inspector Hunkeler believes that the brothel owner Garzoni is the culprit. However, his colleagues Madörin and Lüdi are researching the drug milieu. Then prosecutor Suter withdraws Commissioner Hunkeler from the case because of bias. Has Hunkeler grown old? The third film adaptation of a case with the Basel inspector Hunkeler based on the novel by Hansjörg Schneider.

Hunkeler's last official act went awry: a diamond courier evaded surveillance, the goods ended up in the Basel sewage system, and Lüdi suffered life-threatening injuries. Plagued by guilt, pensioner Hunkeler goes in search of the "silver pebbles". Ultimately, even as a retiree, he is ahead of the pack with his sense of the longings of the little people.

Turkish woman Aische Aydin is found beaten to death in her apartment in Basel. Her husband Ali is suspected, but remains silent and attempts suicide. Inspector Hunkeler cannot accept this. An amulet—depicting a couple in a boat—found at the crime scene catches his attention. Hunkeler has encountered such an amulet before, when he was investigating Roma clans in Alsace. Acquaintances of the Aydins confirm that the amulet belonged to neither Aische nor Ali. Shortly afterwards, Theo, the heroin-addicted ex-husband of a friend of Aische's, is found murdered. The police find a large quantity of heroin. The Aydins are now also linked to drug trafficking.