Seonghyun, the older guy next door who cherished and raised Yeonwoo with great care, returns to Korea after 10 years away. Contrary to his expectation that Yeonwoo would welcome him warmly, Yeonwoo avoids him and treats him awkwardly. Feeling hurt, Seonghyun drinks too much and later visits Yeonwoo’s house. Following a strange sound he hears from somewhere inside, he opens a door and— “Baby… why do you have a vagina?” He discovers the secret Yeonwoo has hidden for so long. Yeonwoo trembles in fear, convinced that Seonghyun will hate him, but Seonghyun instead embraces and comforts him. From that day onward, Yeonwoo slowly opens his heart, and the two develop into lovers. But their peace is short-lived. A stalker who knows Yeonwoo’s secret begins invading their quiet everyday life, bringing about a new and dangerous turn of events that threatens to destroy everything they have built together…