It is summertime and professor Jelínek is spending the holidays in the country with his wife and children, Jarmila, Václav and Ivan. The adolescent Jarmila has her own group of friends with whom she plays sports and goes on trips. Her stable world is suddenly disturbed by the arrival of the arrogant Toufar. His worldly attentions attract Jarmila but make her confused. Her parents travel abroad to a linguists' congress and Jarmila cannot wait to be rid of their over-protective gaze. After their departure the girl decides to visit Toufar at his cottage. At this moment she has a premonition that something has happened to her parents and Jarmila runs away from the cottage. At the same time her mother becomes uneasy and gets out of the train at the next station, taking her husband with her. Jarmila tells her brothers of her fears. In the evening there is an announcement on the radio that the train on which their parents had been travelling has crashed. The children are distraught but assume an air of responsibility, as if they had suddenly become adults. Jarmila looks after her brothers and prepares herself for a life without their parents. Fortunately a telegram arrives in the morning from their parents stating that they are alive and well. Jarmila, now wiser, returns to her friends.
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