Monsters have come to an end, and the world of new humans has begun. The boundaries between monsters and humans are becoming increasingly blurred, and people struggling to survive are all faced with difficult choices.At the end of the previous season, Lee Eun Hyuk (played by Lee Daehyun), whose life or death was uncertain, suddenly appeared.

In Season 3, faced with the conflict caused by greed, the characters who were originally scattered will gather together again:

Cha Hyun-soo (played by Song Kang) wakes up and finds that he has become a monster;

Byun Sang-wook (played by Lee Jin-wook)'s body was occupied by Zheng Yi-ming; Seo Yi-kyung (played by Lee Shi-yun) became half-human and half-monster; Lee Eun-hyuk (played by Lee Da-hyun) emerged from the cocoon of a violently shaking monster;

Lee Eun-you (played by Go Min-seo) perseveres and continues to search for his brother Eun-hyuk;

Private Park Canyoung (played by Jung Jin-young) returns to the field;

Staff Sergeant Zhuo Renhuan (played by Liu Wuxing) still conceals the fact that he has symptoms of monsterization; Dr. Ren (played by Wu Zhengshi) has shown unusual interest in monsterization;

Sergeant Kim Young-hoo (played by Kim Moo-yeol) meets new survivors on Yuldo Island; a girl (played by Kim Seil-ah) who has the ability to turn others into monsters appears.