Yeon-ja is happy with her accomplished family. Her husband is an executive director, her son a professor-to-be, and her daughter a medical student. But she worries about her second daughter, Eun-ae. After presenting "Joy," a senior-focused AI program she developed over five years, Eun-ae receives an investment offer from Kangsu Construction. Meanwhile, Gyeol, a rising architect who won a Young Architect Award in New York, receives an X-ray from his grandfather, the chairman of Kangsu Group.