On Saturday, the big music festival will take place in the city centre and the Boombastic Ninjas will play on the stage in the pedestrian zone. But unfortunately the festival management made a mistake and the stage was double booked. Now the Boombastic Ninjas are to share a stage with the Accordion Grandpas and play only a quarter of an hour each instead of a half. With sweets and a fair amount of charm, the Ninjas set off for the senior citizens' residence to convince the grandpas to let the Ninjas take the stage. But the old-timers stubbornly refuse.