For ten years, police major Vasilisa Zhuravleva has been trying to unravel the mystery of her sister Nika's disappearance. Quite a few girls, "night butterflies" from the highway, similar in type to Nika, have disappeared in Zalesye. But the authorities refuse to look for them and unite them into a series. But when hunters discover the body of another young blonde in the forest, Vasilisa gets a chance to open a case and begin an investigation.