Spring 1986: a nuclear reactor explodes in Chernobyl and emotions run high in a small town in western Finland. Mimi is the new girl in class and suddenly fills 15-year-old Mariia's life with radiant light. The two kiss on the beach and experience their first great love. It doesn't matter to either of them that they come from different social backgrounds. 20 years later, Mariia returns home to look after her seriously ill mother. And the memories of that summer come back to life.