After a critical intelligence leak, a national security unit launches an intensive investigation. But successive setbacks in their arrest operations reveal a shocking truth: the trail leads back to within the unit itself. Amidst a storm of trust and betrayal, a silent battle begins to unfold...

Lin Xiang and Lan Fang, who is pretending to be his wife, are sent to Shanghai to rebuild the underground headquarters and help liberate China from the Japanese invaders.