Margreta Mai, proud owner of the garden café Radieschenheim in the Lübeck area, is horrified: the vice-chairman of the eponymous allotment garden association is found dead in her herb bed! When the grumpy Commissioner Jan Knutsen, who is also her daughter Marjolein's future father-in-law, denies her access to her own garden, Margreta has had enough. She decides to investigate on her own, causing not only her Radieschenheim to be thrown into turmoil.