Stalinist Russia. Leo Stepanovich Demidov (Tom Hardy) is a young officer of the Ministry of State Security quickly creeping up the career ladder. He is an obedient servant of the system, but one day his faith in the ideals of the Party is upset. Superiors make him cover up the cruel murder case four boy. When they begin to die more children, risking the wrath of his superiors, Demidov started an investigation on its own.