S1·E41 The Hand Signals

Sword Fraternity assassins nearly kill Dong Yi but then stop when she says that she is the daughter of the original Sword Fraternity leader. Dong Yi later meets Gae Doo La who refuses to stop what he's been doing. Jang Moo Yeol meanwhile informs the King that the exiled Namin leaders have given their wealth to the poor in order to atone for their mistakes. They are all invited back by the King. Jang Moo Yeol then realises that something is not right because Sword Fraternity assassins kill the guards but not Dong Yi. In the meantime, Dong Yi who has been working hard to investigate the hand signal finally gets her breakthrough. She realises that the signal uses music notes and it spells out Oh Tae Seok's name.