Taboo: Forbidden Love

Eun-ji is a idol trainee who gets abandoned by Jin-tae her sponsor, so she heads back down to her sister Sun-yeong's home. Her first love Joon-hwan is now her brother-in-law so he welcomes her but Sun-yeong treats her like a child and worries that Eun-ji might go down the same path she did when she gave up becoming an idol. Eun-ji and Sun-yeong quarrel often and Joon-hwan comforts Eun-ji every time. Eun-ji starts to depend on him and he also secretly tells her why he quit his job.
One day, Sun-yeong goes on a business trip for a week but before she leaves she tells Eun-ji how sorry she is. They share a momemtum with two wooden dolls.
All alone by the two of them at home, Eun-ji tries to embrace Joon-hwan's heart by showing him a scrap note she made of his articles. He is grateful for Eun-ji and starts to open up to her. The two of them cross a line that should never be crossed and as time goes, they fall deeper and deeper into each other. However, a week passes and Eun-ji feels even jealousy towards her sister because she wants Joon-hwan. Joon-hwan also feels confused and is sad that the time to say goodbye is near. The two of them decide to create a memory they want to give to each other. Eun-ji then feels bad about herself and leaves the house. Joon-hwan takes out his baseball glove and is determined for a new start. Sun-yeong finds Joon-hwan pitching on his own and he tells her everything before going back to their normal lives.