There is an abandoned railway track behind the school, which is Song Shiyu's secret base. She often read poetry there, until one day, a chalk drawing appeared on the railroad tracks - it was the picture of her reading. After that, every evening, there would be another painting there, corresponding to the poem she read the day before. Song Shiyu began to look forward to this silent dialogue and left his own response next to the painting. She finally found the person who painted the picture - Wen Zhiyun, an illustrator in the next class, a teenager who had dropped out of school due to heart problems. They don't talk about the future, they only share the present. Wen Zhiyun told her that his heart could only beat for another three years. Song Shiyu said: "Then I will use these three years to tell you the dusk of the whole world." At the end of the story, the railway track was covered with paintings on the road they had traveled, and the last painting was a heart full of flowers.
