Criminal psychologist Seonkyeong has two new people in her life.

A serial killer whose gruesome murders shook the world but who has steadfastly remained silent. Until now.

A young, innocent looking stepdaughter from her husband's previous marriage, who unexpectedly turns up at the door after the sudden death of her grandparents.

Both are unsettling.

Both are deeply troubled.

And both seem to want something from her. Can she work out just who is the victim in all of this? Before it's too late...