The core of "The Shadow of the Tree Before Flowering" tells the story of Su Nian, a girl suffering from chronic progressive interstitial pulmonary disease, and the gentle respiratory doctor Lu Shiyan, who met in the hospital: When Su Nian first met Lu Shiyan, she was frightened and uneasy because of her condition. Wutong's whispers gently comforted her, and the two gradually developed feelings for each other, and agreed to wait for the sycamore flowers to bloom in April together; Su Nian recorded the growth of the sycamore buds in a sketchbook, and Lu Shiyan looked for a treatment plan for her, but it was difficult to overcome the twists and turns of her illness, and Su Nian eventually passed away before the flowering period. Lu Shiyan planted the "Nian'an Tree" in memory of Su Nian. Many years later, he and Lele, a little boy who was influenced by Su Nian's story (later became a respiratory doctor), led the patients to protect the Nian'an tree every year and tell about Su Nian's courage, so that the promise of "waiting for the flowers to bloom" and the hope for life are passed on year after year like the sycamore flower, interpreting the healing core of "the shadow of the tree does not reach the flowering period of the year, but the flowering period lasts forever".
