Facing financial ruin, Jang Tae-sang agrees to track down a missing person — but two figures trail him. Meanwhile, sinister operations occur underground.

Yoon Chae-ok and Yoon Jung-won find a lead on Myeong-ja, leading them to a hospital. Soon, a calamity traps the two inside, leaving Tae-sang concerned.

Tae-sang decides to reenter the hospital, but discovers that Ryu Sachimoto is nearby. At the hospital, Chae-ok and Jung-won devise a risky rescue plan.

Reunited in their search for Myeong-ja, Tae-sang and Chae-ok attempt to also save other survivors. But soon, the monster makes itself known.

After coming face to face with the creature, Tae-sang and Chae-ok get captured. But as one plans his escape, the other stays to find a person dear to her.

Tae-sang steadfastly remains to save Chae-ok and the captives. On a mission to find her mother, Chae-ok learns the grisly truth — and confronts the beast.

With only 10 minutes to act, Tae-sang and Chae-ok risk it all to get everyone to safety. But just as all goes to plan, one of them may not get out alive.

An unlikely acquaintance becomes Tae-sang's ticket out of the hospital. After a touching reunion, Tae-sang and Chae-ok encounter a transformed Myeong-ja.

After a series of grisly deaths, Ishikawa finds Myeong-ja in her new state. Tae-sang shares a tender moment with Chae-ok, unaware of her hidden plan.

In order to rescue Chae-ok and stop the atrocity, Tae-sang and Jung-won forge a plan. But just as the coast seems clear, Yukiko Maeda stands in the way.

On a mission to clear his name, Jang Ho-jae searches for a mysterious woman. On the job, Chae-ok encounters a familiar person from decades ago.

While looking for the same person, Ho-jae ends up saving Chae-ok, who's being chased by a mysterious being. Ho-jae begins to wonder more about his past.

Chae-ok agrees to work with Ho-jae to find Seung-jo, but they soon find themselves in peril. Meanwhile, Chae-ok's monstrous instincts begin to surface.

Ho-jae tries to piece together everything that has been hidden from him. Chae-ok discovers that the atrocities of the past continue to the present day.

In his effort to save Chae-ok, Ho-jae makes a momentous decision. Having sustained severe injuries, they must battle through a treacherous escape.

After a test subject wreaks havoc in public, Jeonseung Biotech goes into damage control. Fate drives Ho-jae and Chae-ok to confront the company head-on.

As Ho-jae's enemy threatens to hurt those closest to him, he risks everything to protect them. Will he survive the ferocious beasts and save Chae-ok?