Cheung Kei-sang and the orphan Chau Sai-kai, two young lovers from a village in Southern China, are forcibly separated on their marriage day due to the Japanese invasion. Filled with hatred and vengeance, Sai-kai joins a Kuomintang secret agency, becoming their spy, while Kei-sang ends up in a Communist guerrilla militia and receives training to be their government's spy. It is through this militia group where Kei-sang meets Kong Sheung-hung, another Communist spy. Together, they go on a mission to search for a Japanese businessman, who looks eerily like Sheung-hung...