Anna Chebneva investigates a series of murders, assuming the killer is searching for a valuable jewel that is also being sought by a stranger who appears at the scene of every crime. At the same time, Kama Eger is looking for a stash of jewels belonging to a ballerina, and he’s thwarted by a young employee of the criminal investigation department. As the investigation progresses, they realize that they need each other not only as partners—and their inquiry is connected to the story of the Hyperborean ridge found by Nikolay Gumilyov on a distant island.