I-shin offers assistance with the investigation, but it's unclear why she would help a cop. Su-yeol unravels the origins of I-shin's murderous instinct.

The culprit begins to close in on Su-yeol's family. I-shin pressures Su-yeol to take action — but she happens to be the one threatening his family.

Su-yeol finds I-shin in his home after she vanishes under police watch. The killer demands to speak to I-shin and gives her a hint about the plan.