In 1991, the Soviet Union collapsed, and the socialist countries that were originally under the Soviet system declared independence one after another. The Republic of East Slavia was one of the many new countries. However, East Slavia was severely polarized and the society was seriously unbalanced. The rebels and government forces had been at war for more than ten years. As time entered the 21st century, the war between the two sides intensified, and there were even rumors that "monsters" had joined in, and the war began to develop in an uncertain direction. In order to investigate the truth about biological and chemical weapons, Leon was ordered to come to East Slavia. In the chaos, he was captured by the rebels, but humans controlled by parasites soon impacted their habitats and cities. At the same time, Ada also came to East Slavia with a mysterious purpose. The war destroyed everything and nourished the devil. Can Leon prevent the situation from getting worse? This film is adapted from the classic video game of the same name.