As the night has fallen and the bustling offices have gone quiet, Xu Qing You and Mo Ling Ze first meet due to a misunderstanding. White-collar worker Xu Qing You spends all year round working so much that it's always evening by the time she packs up to go home. She has been in a long-term relationship with Fan Yun Xi for ten years and was preparing for her wedding when she finds out that he cheated on her. Fan Yun Xi explains it was an accident yet Xu Qing You resolutely asks to break up.

While investigating a murder in the old city, Public Security investigator Song Xingye uncovers a hidden conspiracy. Teaming up with his tech-savvy assistant Zhen Na, tough police officer Shang Wei, and the mysterious heiress Zhao Qingyun, he races against time to expose the truth and stop a looming coup.