Life for human kind was not easy and all because of one thing; the surface now belonged to a superior race. A race of shape-shifting mutants that claimed the surface. Every bit of dry land, every place the sky was visible, every place humans built houses and lived happily, it all belongs to them.

But humans didn't give up that easily. They now live in the depths of the ocean, in domes that protect them from the dangers of the sea and supply the necessary conditions and resources for survival.

Still, some humans refused to give up their precious land so easily and managed to sneak underground.

22 year old Kim Kibum, also known as Key, was lucky enough to scurry down to one of the underwater cities for lower class civilians. He found a job as a scouter, notably not one of the best jobs out there.

But one day during one of his missions, a dangerous yet fascinating encounter happens. He comes face to face with an odd specimen, one of the mutants. What happened after that encounter?