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 and her mother are trying to survive this difficult period in a small run-down flat in Wanchai. After the schools are closed, Lan unwittingly finds herself involved in the guerillas' mission to save novelist Mao Dun. That's how she meets Blackie Lau, the intrepid sharpshooter captain of the guerillas' Urban and Firearms unit. Taking notice of Lan's calm, smart 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 Wing, who now works for the Japanese.