1941. Hong Kong is under Japanese occupation. The anti-Japanese Dongjiang guerilla unit is tasked with rescuing cultural figures and extracting them from the besieged city. Primary school teacher, Fang Lan (Zhou Xun) and her mother are trying to live out this difficult period in a small run-down flat in Wanchai. After the schools are shut down, Lan unwittingly finds herself embroiled in the guerillas' mission to save novelist Mao Dun. In the process, she meets Blackie Lau (Eddie Peng), the intrepid sharpshooter captain of the guerillas' Urban and Firearms unit. Taking notice of Lan's calm, intelligent nature, Blackie recruits her to join the guerillas. Worried for her daughter's safety, Lan's mother volunteers to take Lan's place as a courier, only to be arrested on the job. To save her mother, Lan is forced to turn to a friend, who now works for the Japanese…