It is set in the Imperial Japanese puppet state of Manchukuo in the 1930s before World War II erupts.

[4] Set in the Japanese puppet state of Manchukuo, the film follows four Chinese Communist Party agents who parachute back to Harbin[5] in Northeastern China in the early 1930s.

Together, they embark on a secret operation code-named “Utrenya” (Russian: утреня) that intends to extract a former prisoner who could expose the unethical human experimentation and other crimes against humanity committed by Unit 731 of the Imperial Japanese Army in front of the international community.

They are also ready to sacrifice themselves by ingesting cyanide-equivalent pills contained in a match box.

They manage to escape the trap, but also realize they had been sold out by a traitor, who caved after being tortured and witnessing the execution of his fellow comrades.