When the world transformed into an uninhabitable, chaotic place eight years ago, a group of scientists created a serum that served as a solution to humankind. The serum was supposed to reprogram people to do the right thing so that they can fix and strive on earth. However, things didn't go as expected, as the serum made them into robots. It erased people's memory and their capability to have free will. It reprogrammed the way humans think. Some were able to escape and survived, but some were not so lucky.

Choi Haerin was able to escape after her memories came flashing back. She spent five years living inside that hell hole, doing the same routine every single day while being unable to remember anything from her past. Little did she know, they've tagged her. 

Lee Jeno and Na Jaemin made it out of the camp successfully eight years ago. They've been living outside of the colony ever since. Extreme weather and poor living condition made it hard to live, but they've gotten used to it as time went by. 

Just when they thought that they were safe, the inevitable brought Choi Haerin to them. 

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