This time, Marc, Niki and Rex have to investigate a rather unusual case: Eduard Ettrich, president of a pigeon fanciers' association, was dragged to his death by his favourite pigeon Elli, who had been prepared with a letter bomb. Ettrich's son Gernot also died a short time later in such a terrorist attack ...

A certain Elvira Strasser writes a letter to Niki from prison asking for a visit - but this is no longer possible because the woman has taken her own life. Niki decides to go undercover to prison - she doesn't believe in the suicide theory. She finds out that the supposed suicide was clearly a murder...

18-year-old Thomas and Lisa, who is still underage, have been secret lovers for quite some time and - without anyone knowing about it - are expecting their first child shortly. The two disappear without a trace after a party at a friend's house that ended with the murder of a young man named Manuel...

Mr. Walter is a full-blown disgust: He clearly enjoys tyrannizing nursing staff and roommates in his retirement home - now he has been murdered! When Marc begins to investigate this case, two main suspects immediately emerge: Walter's son Robert and the wheelchair user Färber ...