Gu Wantang, an ordinary modern office worker, picks up Xiao Nian'an, a little girl in ancient costume, on a rainy night and discovers that the child can travel back and forth between modern times and the fictional Dayan Dynasty. Through Xiao Nian'an, Gu Wantang supplies grain, medicine, materials, and modern tools to Crown Prince Xiao Linyuan and his remaining soldiers, who were deposed by his imperial uncle and trapped in Eagle Beak Cliff. This helps them gain a foothold, develop infrastructure, subdue refugees, and repel rebel forces. In cross-time-and-space rescues, Gu Wantang falls in love with Xiao Linyuan, ultimately welcoming an imperial envoy from the capital as the story continues to unfold.