On October 8th, in the 17th episode of SBS Monday-Tuesday 'Great Doctor', Yoo Eun Su (played by Kim Hee Sun) agrees to marry Deok Heung Gun to save Choi Young's (played by Lee Min Ho) life.
Yoo Eun Su reads the letter to herself from her diary. It said, "The person is heading into a trap. So Eun Su, please stop him." After reading the letter, she realized that Choi Young would die because of Deok Heung Gun's trap.
Yoo Eun Su went to Deok Heung Gun and angrily said to him, "Are you planning on killing Choi Young today? Really? Are you really planning on doing that?" Shocked, Deok Heung Gun asked, "How did you know?" Eun Su shouted, "It was written in my diary. I told you not to touch that person!"
Deok Heung Gun said in response, "Why are you talking nonsense?" He did not believe her so Eun Su said, "What is the trap? Where is it? Let him leave. I'll do anything you want. Please." She cried as she begged Deok Heung Gun.
Deok Heung Gun explained to her that he would kill him with gunpowder. He gave her his conditions and said, "I need to have you in order to get Ki Chul (played by Yoo Oh Sung) as well. However, I cannot have you because Choi Young stands in the way so I need you to marry me, a royal."
Deok Heung Gun wanted to barter for Choi Young's life in exchange for Yoo Eun Su's hand in marriage. Yoo Eun Su accepted his terms in order to save Choi Young. She told him, "So all I have to do is get married to you? Then let's do it."
