An elegant young Lebanese man carrying diamonds in his bag is on the train from Frankfurt to Basel, a drug mule on the return journey. At the Basel train station, Hunkeler is waiting for him after a tipoff from the German police. The courier manages to get to the station toilet and flushes the stones away. Erdogan, a young Turkish sewage worker, finds the diamonds in the pipes under the station. To him they mean wealth and the small hotel he always wanted to buy near his family village. To his older Swiss girl-friend Erika, employed at a supermarket checkout counter, the stones signify the end of their life together. She knows that Erdogan has a wife and children in Turkey. For the courier, finding the stones is a matter of life and death. His employers are on their way to "tidy things up". For Hunkeler the stones are the only way to get to the people behind the drug trade. They turn out to include not only the bottom-feeding drug gangs but bankers and politicians very high up the Basel food chain.