Senior Lieutenant Valery Samsonov is on the trail of a sophisticated, bloodthirsty killer, at whose hands two employees of a pharmaceutical company have already died. Someone is systematically and brutally killing those associated with Operation Ultraviolet - the development of a unique medicine. But something went wrong with the scientists, and instead of the necessary drug, they created a deadly weapon, the materials for which under no circumstances should fall into the wrong hands. Samsonov must at all costs prevent new victims, but the matter is complicated by the fact that the investigation is supervised by inconspicuous people from the special services - the security of the country is at stake...