What it is to be human doesn't apply anymore. The surface of the Earth has been poisoned by years of abuse and now most life lives beneath the waves of the ocean. Over the last 500 years, humans have become fragmented and specialized by genetic manipulation, but two main factions exist in the Undersea. The hybrids, a race that continues to genetically modify themselves to climb the social ladder, and the humans, the unmodified organic race that makes up the lowest tier of society.After Jack’s heroic rescue, Alex struggles with an impossible choice, her long lost love, Tom or her passionate partner, Jack. Meanwhile, Henry, Alex’s husband, launches missiles at their new base and sends Alphas in pursuit. Jack makes the difficult decision to leave the Surface in order to prevent future attacks and befriend Henry. Alex, left behind, struggles to defend the base. Eventually failing, she and Lexi desperately search for a new home.