Lin Xingyue, a computer prodigy with social anxiety, spends most of her time in a server room kept at 26 degrees. Online, she's an anonymous tech genius admired by all; offline, she's quiet and withdrawn, hiding every flutter of her heart and every tender thought in code comments and draft folders. Rock guitarist Lu Chenfeng is torn between the finance career his father mapped out for him and his dream of making music, forever trying to tune the third string that never stays in tune.
At a music festival in early autumn, a manuscript slips from someone's hands and is mistaken for a love letter, quietly bringing their two worlds together. They come to know each other anonymously online and slowly grow closer in person. They sit in quiet companionship four shelves apart in the library, and stay by each other's side across a seven-hour time difference. Withered leaves on a windowsill, tart tangerines with a lingering sweetness, and red bean milk tea gone cold become romantic tokens that belong only to them.
Neither asks the other to change. They simply take their time adjusting to one another. She supports his musical dreams with her reason, while he embraces her social anxiety and reserve with tenderness. Su Qing makes a graceful exit, and father and son reconcile through small gestures. Little things gradually settle into an enduring bond. On the night of their graduation performance, code effects slowly light up, delivering the most heartfelt confession: You are the only constant in all my programs. From their shy school days to building a business together, once this love is defined, it remains constant for a lifetime.
