Mercury mutant Jae-jin is excited to play with the Protein Monster.Eun-you is caught in the crossfire and Hyun-soo the monster impatiently goes to save her.After a fierce battle, Hyun Soo finally defeated the protein monster.Jae Jin excitedly wanted to meet Hyun Soo, but Hyun Soo cut his hand.Hyun-soo notices that Jae-jin is weak and drags him over after learning that Nam Sang-won is at the gym.Three masked mutants show up at the gym looking for someone, and Minami Aihara arrives and kills them.Afterwards, he asks his daughter what she wants in return, and the scene cuts to her taking back Ying-soo's baseball from the bully and taking a kid's glove to put on.Yi Kyung finds her daughter and pulls her into a hug.In the secret exit ventilator, Yi-kyung apologizes for everything, saying she doesn't hate her and was once scared, but hopes her daughter will give her a chance.She would wait in the air duct and if her daughter decided, they would leave together.

Minami Aihara locked up the masked mutants and they turned into pupae.In order to prevent Nam Sang-won from getting angry because of the soldiers looking for Sergeant Kim, Sergeant Zhuo confessed that he was infected and won Nam Sang-won's trust.The mutant asks Sergeant Zhuo if he has seen pupae, as they attract the masked mutant.The soldiers discovered that Squad Leader Chi's son had turned into a pupa.Minami Xiangyuan told Sergeant Zhuo that these masked mutants claiming to be New Humans were harassing them, but they would turn into pupae and be reborn every time they were killed.He's been killing all the mutants who come looking for something.The Doctor is interested in the glowing, beating pupae.After Sergeant Zhuo exposed himself, he rushed to find the doctor to discuss the next steps for his complete mutation.The Doctor shows the chrysalis shell and says that Sergeant Zhuo needs to fight a new human before fully mutating.

In the church, Eunhyuk says that chrysalis are like hearts, and in addition to being reborn, they are also quick learners.He tells Sergeant King that this is the next step in evolution, but mutants threaten them.The new humans just want to find others of their kind and try to survive.Eun-hyuk asks Sergeant Kim to take him to the gym.As Sergeant Kim gathers supplies, Eun-hyuk finds family photos in old clothes and takes them.Sergeant Kim asks him if he remembers human memory, but Eun-hyuk avoids answering.Eun-yo reunites with Chan-young and Ha-ni and heads to the gym because she believes Hyun-soo is there.Jae-jin is confused about Hyun-soo's behavior, and the monster Hyun-soo says it's all for human Hyun-soo.At this time, Jae-jin's hand regenerates and he burns Hyun-soo before running away.Meanwhile, Young-soo discovers the baseball that Yi-kyung’s daughter got for him.He advises her to go with her mother without regrets and gives her the pin that Mr. An gave to his late sister.Someone seemed to hear it.

In the tunnel, Yi-kyung’s daughter asks Yi-kyung if she has a name.Before they could answer, Minami Aihara found them.In what looks like a touching reunion, he hugs Yi Kyung and she puts down her pistol.But then she stabs him and tells Yi-kyung's daughter to run away.He angrily attacks both men.In desperation, Yi-kyung begs him to take her, but he reveals his true colors, snarling that her worth ends the moment she gives birth to the mysterious girl.She shoots him in the face in an attempt to get the mysterious girl to escape.Yi-kyung reveals her daughter's name is Seo Yi-soo, at which point Nam Sang-won fatally stabs Yi-kyung.Yi-soo cries, takes off her gloves, and tries to transform Yi-kyung, but it doesn't work since she's dead.