Contains spoilers for this episode and earlier episodes.
Won-deok asks Do-san to keep her failing eyesight secret from Dal-mi and Ji-pyeong. She wants to enjoy seeing her granddaughter happy for as long as she can, and thanks him for giving Dal-mi reasons to smile. Do-san realizes that Won-deok is the woman whose kindness Ji-pyeong wants to repay. His intention to reveal the letters fades, and the two men compete awkwardly over household repairs when Ji-pyeong joins the family for dinner.
At Sandbox, Samsan Tech must decide how to use its limited funds and attract more business. Dal-mi considers a project with Morning Group despite the family's hostility toward Chairman Won. In-jae rejects the suggestion that her own investment came through her stepfather, explaining that she made contacts at the hackathon. Dal-mi prepares a proposal, but Ji-pyeong suspects Morning Group wants to use the young company as a cheap supplier rather than support its development.
The meeting confirms his concern. Chairman Won offers less than the terms Samsan Tech expected and insults Dal-mi's choice to stay with her father. Do-san smashes the chairman's glass nameplate, cuts his hand and walks out. On the roof, he apologizes for losing a potential customer. Dal-mi kisses him and supports a different project: combining image recognition with a voice service for people with impaired sight. Do-san's idea grows from Won-deok's condition, which Dal-mi still does not know about.