The story follows 10-year-old city boy Chen Yuxuan, who participates in an experiential reality show and travels to a rural village in Hebei's old revolutionary base area. Due to his spoiled and lazy nature, Chen Yuxuan struggles to complete the tasks assigned by the production crew. During this time, he accidentally discovers a "Jimaoxin" (a letter marked with a feather as a sign of urgency). The letter's owner, Grandpa Zhao, takes the opportunity to tell him the story of how he delivered such a letter during the war against the Japanese invasion and counter-mopping-up campaigns. As the show progresses and the story of the Jimaoxin unfolds, the modern child Chen Yuxuan and the young letter carrier Zhao Haiwa from the past each grow through their respective journeys. Across different times and spaces, the two boys of similar age complete their own missions and gradually mature into responsible youths.