While investigating a homicide case, police officer Zhuang Shu unintentionally discovers that his childhood friend Li Fei is also involved. Zhuang Shu was reunited with his childhood sweetheart Li Fei while he was pursuing a murder suspect as she might just be the witness to the case. Eight years ago, the two made a promise to meet on Christmas Eve but lost contact due to an incident. Layer by layer, their past unravels to reveal a stubborn teen who was at odds with his family and a young woman who wanted to leave everything behind. In the face of an unfulfilled promise, the confusing truth and the intricate relationship between two generations, everything gradually becomes clear. Adapted from the novel "Moses on the Plain" (平原上的摩西) by Shuang Xue Tao (双雪涛).