It's early summer. A young couple with their eight-year-old son arrives at their dacha. Someone has broken Mom's favorite blue cup. The cup is broken, but no one broke it. So what happened? This mystery gives rise to a vague premonition of something irreparable. Father and son, hurt by the unfair accusations, decide to leave home—for good. A drama based on the story “The Blue Cup” by Arkady Gaydar.