Undercover Lu Yan returned from nine years of guarding the border. After returning home, he discovered an unusual crisis at home from his wife's Morse code. The couple has a close heart and a tacit understanding of each other. With the help of their comrades, they calmly deal with the layers of surveillance, cleverly escape tracking, and protect the safety of each other and their families. They fully demonstrate the responsibility and perseverance of an undercover agent, and also explain the deep affection between a couple who share weal and woe.
