Under mysterious circumstances, the director of a travel agency, Lyudmila Khankina, dies at night. Yana, an accidental witness to the murder, can’t—nor does she want to—stay indifferent. And nearby the corpse, they find several uncut diamonds. The investigation determines: the victim was poisoned with batrachotoxin—a rare poison produced by African frogs. Yana and Margosha, helping with the investigation, uncover an “diamond route” from South Africa to the nearby Moscow region. They learn about a mystic hermit—an diamond collector, about a chain of murders and suicides, a fake will, falsified evidence—and, above all, that the pink diamond is no longer sparkling on the killer’s hand…