Hwang Jung Eum learned of Ji Sung's strategy too late.
On the 7th episode of KBS 2TV Wednesday/Thursday drama "Secret" (Script Yoo Bo Ra Choi Ho Chul, Director Lee Eung Bok, Paek Sang Hoon), Kang Yoo Jung (played by Hwang Jung Eum) learned of Jo Min Hyuk (played by Ji Sung)'s strategy.
On this day, Kang Yoo Jung met Hye Jin (played by Moon Ji In) coincidentally on the street and slapped her, showing her her anger. This is because there was a time in prison when she had put the blame on Kang Yoo Jung by abusing Kang Yoo Jung's son San Yi when he wasn't there.
Kang Yoo Jung thought of San Yi who was already dead and asked Hy Jin why she had done this. Hye Jin was alarmed that San Yi had died and said, "You had only asked to now be on parole. Were you ever hated by anyone?"
Kang Yoo Jung thought of what Hye Jin said and thought of Jo Min Hyuk. Jo Min Hyuk had been contemplating revenge after Kang Yoo Jung after losing lover Suh Jin Hee (played by Yang Jin Sung). Jo Min Sung especially said it would be best to go visit prison while Kang Yoo Jung was in prison. Kang Yoo Jung later learned of Jo Min Hyuk's plan to have her distraught and was shocked.