In 1949, on the eve of the national liberation, Xiamen, as the last stop for the National Government to flee to Taiwan, staged a tragic life-and-death spy war. Huang Cansen (played by Lian Kai), a young captain of the Kuomintang army, fell deeply in love with Li Laiya (played by Zhang Zheng), a piano teacher at the Church Women's College. But Li Laiya was an underground worker of the Communist Party, and she passed on various intelligence information without anyone noticing. As the war approached and the Kuomintang was doomed, Huang Cansen hoped that Li Laiya would go to Taiwan with him. Li Laiya and Huang Cansen agreed to meet at the "Black Cat" bar. But just before the meeting, Huang Cansen was ordered to be responsible for shooting the pianist in the "Black Cat" bar. Huang Cansen went to the appointment with a pistol filled with bullets... More than 60 years later, in 2012, on Gulangyu Island in Xiamen, A Ming (played by Zhang Mo) and Li Qingzi (played by Lin Yixin) were a couple who had been in love for many years. Li Qingzi practiced piano on Gulangyu Island, hoping to study abroad one day. Wang Amin, a master hacker, stays at home all day, immersed in his own network world. He finds the greatest pleasure in cracking various network keys and breaking into the tightly guarded hidden network space. By chance, Amin finds a half piece of music engraved on a tombstone erected in 1949. This is a coded song, and Amin cracked the secret. From then on, Amin's life was involved in a "dark curtain", and he was even inexplicably hunted by a killer (played by Power Train)...