In the summer when Qing Ning entered middle school, she met Lu Yan, who looked very similar to her childhood friend, and became friends with him. Later, she met Mo Qing, who had a low self-esteem, and An Zixi, who was lonely and arrogant. Under the influence of Qing Ning, they gradually became sunny. Qing Ning's story began. It turned out that she once had a good friend who accidentally lost his life in an accident. Qing Ning and his partners found a way to go back to the past. Can they save Qing Ning's friend?