A senior lieutenant Valery Самсонов follows up the scent of acute blood-thirsty killer, from the hands of that two employees of pharmaceutical company perished already. Someone systematic and cruelly kills those, who relates to the operation "Ultraviolet" - to development of unique medicine. But something for scientists went not so, and instead of necessary preparation they created a mortal weapon, materials on that nowise must not get in stranger hands. Самсонов must by all means prevent new victims, but business is complicated by that investigation is supervised by imperceptible people from the special services - on kitty safety of country.