Since his wife left him, Hannes Herbst happily focused on running his old-timers garage, racing rallies in them and old-fashioned hobbies in his TV-free home. Then his sister Esther Wortmann, estranged years ago by deserting their dying father, arrives unannounced, expecting he minds her rascal sons Jonathan `Jona` and little Bruno, `while she is examined in hospital`. He accepts very reluctantly, disliking any disturbance to his meticulously planned domestic life, and is furious when she`s scheduled for surgery and long recovery. Trapped, he relies on a disliked tenant to coach him at child-care, but slowly grows protective and even fond of the equally unamused scamps.