During the 2nd Sino-Japanese War, orphan Lu Feng returns to Shanghai as a Communist undercover agent, tasked with infiltrating No. 76 Headquarters. There, he crosses paths with the mysterious Hua Xiang Yu and his childhood friend Huo Fei, both hiding secrets of their own. As they circle each other in a dangerous game of loyalty and deception, these hidden agents must decide what they truly stand for, risking everything to fight for a better future.