Margaritka (Daisy) is sick during the school year. Her dad is a writer and her mom is an actress who is rehearsing her lines for a new premiere. She is having an affair with the director of the production. At the premiere of "Mommy," Daddy sees her and the director kissing. Papa and Margaritka leave without waiting for Mommy. At home, a scandal is inevitable, but it does not solve anything yet. Mama leaves on tour, and Margaritka and Papa go to the village. There she makes friends with the village children and forgets about her incessant coughing and sneezing. Soon she begins to miss her mom and asks her dad to call her. He writes a telegram but does not send it. The child finds a crumpled piece of paper and goes to the post office. Mom arrives and all three are reunited.

A geologist engineer Yuliya disappears. Ablamov, an elderly engineer, organizes a rescue party to look after her in the mine galleries but they find nothing. Yuliya was last seen at a ceremony for award-wining miners. The newsreel crew was filming the event. Yuliya left in the middle of ceremony. Prodanov, a headstrong and quarrelsome engineer, had followed her. Suspicion falls on him. However, the film sequences shot at the ceremony reveal that Ablamov reacted suspiciously to Yuliya's exit. Detected as the murderer, Ablamov attempts to cross the border but is caught. Yuliya had discovered that the ore contained uranium. Ablamov had replaced the samples in order to prevent the development of the uranium ore deposit.