Episode 7 - S1.E7

So Young finds out that the tattoo on Da In and Dae Soo's wrist are the same as the stamp pattern of an old amusement park. She believes that this case has something to do with the amusement park and its related case that Gu Cheol was in charge 16 years ago. When Gu Cheol in informed of what So Young has found, he seems to be shocked and somewhat anxious.