Zondag de Negenste tells the story of brothers Horst (Josse De Pauw) and Franz (Peter Van den Begin) who see each other again after a life full of missed opportunities. Horst suffers from a lack of joy in life and Alzheimer's. Franz needs money and is hoping for his brother's inheritance. The film weaves together the memories of two brothers with those of the residents of a residential care center, and in doing so, tells in a unique way that caring for each other may be the most essential form of humanity.