The story takes place in 1945 in Chongqing, the wartime capital. Xu Zhongyi (Sha Yi), a student at a Kuomintang special training school, is held back a year and ordered to join the Military Statistics Bureau in Shenyang. His mission is to infiltrate Communist forces as a spy. Chen Ming (Zhao Chunyang), head of the Bureau's Shenyang station, knows nothing of this and suspects Xu's sudden return to the Northeast. Xu cleverly sets a trap to allay Chen's suspicions. Xu had been forced to join the Bureau, and was gradually moved by the Communists' spirit of benevolence and righteousness. In the end, he surrendered to the Party. After a rigorous investigation, the Party decided to have him work from within the enemy's ranks for its cause.
