Jana and Sofia were best friends when they were schoolmates. Now Jana is a commander in the Slovak police force and Sofia, having made a name as a reformer, is a member of parliament. Jana has fallen in love with an upright government prosecutor and Sofia is carrying on a notorious affair with a suave, married fellow MP.

One day Jana finds an enormous diamond gem dangling from a string fixed to the ceiling of the living room of her house. Was it put there as a present? Or, more likely, to entrap her? The answer leads Jana across Europe to unravel a criminal conspiracy involving multiple murders that has entangled her hapless, impulsive friend, Sofia, and which ultimately leads to the criminal mastermind.