In 1933, an agent codenamed "Ghost" led the resistance movement against Japanese colonial rule. In order to prevent the "Ghost" from assassinating the Governor-General, the newly appointed Captain of the Guard (Park Hae-soo) set a trap to catch the Ghost in the Governor-General's Office of Korea. In this way, five suspects were kidnapped to an isolated hotel. They are: Murayama (Sol Kyung-gu), the supervisor of the Communications Department of the Governor-General's Office, Ji Kyung (Lee Ha-ni), who records the code, Lily (Park So-dam), the secretary of the Director of Political Affairs, Cheon (Seo Hyun-woo), who interprets the code, and Baekho (Kim Dong-hee), a staff member of the Communications Department. The Captain of the Guard must find out the true identity of the "Ghost" within a limited time of one day. This work is adapted from the novel "The Sound of the Wind" by Mao Dun Literature Award winner Mai Jia.