Si-o vows revenge after discovering the truth about Nam-soon. While Hee-sik continues his investigation, Nam-soon and her family go on a trip to Busan.

Mourning the loss of Hwa-ja, Nam-soon directly challenges Si-o. But he refuses to lose, forcing her to endure incredible pain to save her adopted mother.

With Nam-soon on the brink of death — Hee-sik rushes to find an antidote. Nam-soon faces Si-o once again, but witnesses a surprising turn.