Dong He’s 70 years old but he’s a dynamic old man, at the cutting edge of technology! He cooks with his tablet, masters his social networks at his fingertips and enjoys life to the full. But overnight, his son decided to leave for the United States to remarry and leave his son, Jae Hun, behind, whom he entrusted to Dong Il. His somewhat unconscious lifestyle was then challenged by the arrival of Jae Hun in his daily life. And when, in addition, older people start to be targeted for crimes, Dong Il and Jae Hun will become budding detectives.