Ryu Seorin is a serial killer. A murderer who killed 8 people over the course of a year.

The police couldn't find even a single clue for the investigation.

Thus, Ryu Seorin's crimes remained cold cases.

However, recently, Ryu Seorin hasn't committed any crimes. She was too busy, and it was too much of a bother.

It has been two years since Ryu Seorin last committed a crime. Suddenly, her desire grew. She wants to see blood.

So, Ryu Seorin planned for three days and murdered a man.

Then there was the man's wife.

She was hiding in the bedroom closet, holding her breath. It soon became quiet, and after some time passed, she slightly opened the closet door.

And she saw Ryu Seorin, who had slaughtered her husband and scattered him on the bed, quietly staring at the closet.

Confirming her presence, Ryu Seorin dragged her out of the closet and assaulted her. Indiscriminately.

After enjoying herself as much as she wanted, she stabbed a knife into the wife's leg.

She attached a post-it note to the knife.

I'll always be watching, ma'am.

She left her alive. Ryu Seorin knew the wife was blind.

Next day, the victim's wife woke up and ran out of the house screaming.

The police arrived and realized the crime pattern was identical to the serial killings from two years ago. An investigation began.

And that blind woman is always being watched by Ryu Seorin.