An Evil Soul (1998)

A Taiwanese female teacher Nie comes to South Korea to teach kids her mother tongue language to develop equal cooperation between the nations. During her class her co worker Zhao Yuhe turned out to be a North Korean defector and kidnap some of her students and flee to the north. Since there is no chance for the kids to return the school blames Nie as a scapegoat for avoiding lawsuits. Nie get sentenced to prison. Under the parole she learns how to mix chemistry and figure a plan to take revenge on the school by giving all classes false medicine. But the plan goes too far as all the kids get killed by the pills including her own niece Chaoxing. Now she understand there is no escaping if one make a packed with evil.