Geun Jungwon is the most famous successful and well-settled businessman. Geun Eun-Hee is also known as a famous surgeon.  After completing their university they got married and continued their careers. 
They were happy in their little world but one-day Eun-Hee met Seon Soon-Ja who was attempting suicide. Eun-Hee saved her and brought her into their house. Jungwon wasn't happy with Eun-Hee's decision as he felt something weird toward Seon Soon-Ja but his love for his wife more than anything. 
Jungwon respected Eun-Hee's decision and agreed to let Soon-Ja live in their house, and then something changed all of their lives, something which they never imagined.

Unbearable