Shen Qingying, an underground worker codenamed "Nightingale," received the last hidden mission of becoming herself. Her superiors ordered her to perfectly play the role of "Lin Jianyue" - the legendary agent who sacrificed her life to the enemy, and the Bai Yueguang who was deeply hidden in the heart of the spy leader Gu Chenzhou. With a similar appearance and superb acting skills, she successfully moved into the old house reserved by Gu Chenzhou in memory of his late wife, and became the most affectionate and dangerous phantom around him. She learned Lin Jianyue's handwriting and copied her habits, but in the thrilling dealings and unexpected protections, cracks appeared in Gu Chenzhou's frozen emotions. When he began to wonder why this "substitute" was more vivid than his memory, the organization's secret order suddenly came: Lin Jianyue was not dead and was about to return. And Shen Qingying must personally return everything he got, together with the feelings he has sprouted, to its original owner, and quietly call it quits before dawn. When the real bright moon rises, how should the carefully disguised shadow be placed?
