Kim Hee Sun transformed into a Koryo version of Mata Hari. 

SBS revealed a still cut of "Great Doctor" on Sunday and in the picture, Kim Hee Sun is wearing traditional Koryo gear, complete with the decorated clothing and fancy jewelry, including earrings and a head piece. This is for their new operation titled 'Mata Hari.' She had originally told Choi Young (Lee Min Ho) that she would recover the diary by using 'Operation Mata Hari.' Mata Hari is a female spy who was active during World War I. 

People are wondering what kind of plans she will unfold in order to save Choi Young's life. 

A representative "Great Doctor" said, "In the 17th episode, Yoo Eun Soo will try her best to save Choi Young and the two of them will get closer."