A high ranking executive defector from North Korea was killed abroad and South Korea sends out an alert for the safety of the North Korean defectors. 　　Detective Kim, who is responsible for keeping the identities of the defectors safe, can’t find Ryoo Soo-hyeon who has been out of reach for a month. 　　Ryoo Soo-hyeon was working part time in a library. One day, he received a letter ... (展開全部)