Contains spoilers for this episode and earlier episodes.
Moon-young and Sang-tae's work leaves Gang-tae feeling excluded on his day off, until a visit to Jae-su brings her rushing over. Their conversations about the future sit beside a more troubling discovery: Gang-tae finds a threatening butterfly message at the mansion. He encourages Sang-tae to stop running, and his brother receives another reason to consider that choice on a bus. Construction noise frightens veteran patient Mr. Kan, who relives his wartime memories. Sang-tae covers him with his jacket, reassures him and asks someone to call the hospital. The encounter gives Sang-tae a chance to protect another person, and afterward he agrees to describe the night their mother died.
Sang-tae remembers a woman wearing a distinctive butterfly brooch and threatening him after killing his mother. Gang-tae connects the description to a photograph of Moon-young's mother and fears that their families' losses are joined. He injures his hand in frustration and becomes distant when Moon-young suggests taking a family portrait. With Director Oh, he finally admits his suspicion and his fear of hurting both Moon-young and Sang-tae. Moon-young has also described seeing her father's violence and remaining unsure whether her mother died or vanished. Moon-young and Sang-tae go to the photography studio without Gang-tae, but he arrives dressed for the portrait and joins them.