The joy is great when Mario Kopper meets Sandro again on the street, his closest childhood friend, who later ended up back in Sicily. The two are about to celebrate their reunion in a pub when Sandro is suddenly attacked by a guest. Kopper takes up arms, Sandro can flee. The frightened Sandro begs Kopper for help: As a tax consultant, he has seen more of the business of the Mafia branch Stidda than is good for him. Sandro is willing to testify as a key witness if Kopper helps him get into the witness protection program. Sandro's fear of Stidda's long arm fits all too well with the case that Lena Odenthal and Johanna Stern are currently working on: a Mafia witness killed himself in the JVA before he could be transferred to Italy. lena, Johanna Stern and LKA Commissioner Manz are convinced that the witness was forced to commit suicide, but cannot prove it. Because Kopper fears that a similar fate is threatening Sandro, he hides his friend,without telling Lena and her colleagues about it. Sandro's panic, but also his own fatal knee-jerk reaction in the pub, prevent Kopper from confiding in Lena. While she is increasingly worried about what is going on with him during her investigation, Kopper tries to bring Sandro to safety as a key witness. However, there are increasing signs that Kopper himself has fallen into the crosshairs of the Mafia.
"Tatort: Kopper" is Andreas Hoppe's last assignment as Mario Kopper after 21 years and a total of 57 films at Lena Odenthal's side. The case is about friendship and loyalty, trust and decision, and Mario Kopper confronts his origins more intensely than ever before, and in which the long arm of the mafia reaches as far as Ludwigshafen. It was written by screenwriter Patrick Brunken, and Roland Suso Richter directed "Tatort". Michele Cuciuffo, a member of the ensemble at the Residenztheater in Munich, can be seen in the lead role in the episode as Sandro, and Saskia Vester as LKA inspector Manz.