Edi Salzer, a homeless man, is found murdered. In order to solve the case Alex and Rex go undercover to mingle with the homeless. The autopsy reveals that Edi was killed by nerve gas and time is running out for them to solve the case.

Tanja Kause has just inherited a painting, what she doesn't know is that a will is hidden behind the frame. When Franz Zehrer is murdered can Alex and Rex get to the bottom of the mystery of old Mr Stift before more people are killed?