Centuries ago, mutation infected every living thing. The world was thrown into chaos and humanity was left with no choice but to seal themselves away in an underground facility. To protect future bloodlines, the surviving population was soon divided by not only intellect, but undeniable genetic superiority.Phylum is a brilliant young biologist with greatness ahead of him, but his status comes with certain expectations. In a rare moment of defiance, he seizes the chance to join a new scientific expedition to the surface. However, when his ambition almost costs him his life, he encounters something extraordinary: A girl, a human girl, living on the surface. Despite her animalistic qualities, she is remarkably intelligent, compassionate and even charming. He begins to fall for her, but the further they explore the vibrant paradise that she calls home, the more he reflects on the life he must return to.