On a rainy night when the performance fails, violinist Jiang Nanxing accidentally breaks into the rain chain maze of demented piano professor Su Wanzhu in a nursing home; poet Lin Buyi uses images as lights to find the coordinates of "gardenia fragrance" and "piano box". Opening the dusty canvas bag, the 1945 war love song "Rain Chain" appeared: She added Chopin's "Rain Drops" and sent it to her frontline lover Chen Shanmu, but she never got a reply. The two rushed to the Invalides with the incomplete music score, and found that the deaf Chen Shanmu was also clinging to the iron box, which contained the manuscript she had sent back that year and the love letter on the back. When "Rain Chain" sounded again, the two old men beat the raindrops together in the air; in the dim light after the rain, the forgotten souls recognized each other through the melody, and the trembling hands completed a response that spanned half a century - music and poetry stitched together broken memories, proving that even if love is late, it is still the last and most gentle line of defense against time.
