Obituary-reading emo girl Edith Small is broken - the end result of forcing herself inside a mold that doesn't fit. All she wants is to conform to her strict sergeant stepfather's rules long enough to make it to graduation day. But a boat accident threatens to unravel the life Edith has worked so hard to keep. After waking up in a hospital with a lacerated shoulder, Edith fakes amnesia. Because admitting she received her injuries from a blue-haired girl who breathes underwater is all the reason Sir needs to send Edith on the first bus to military school. Safe at home, Edith struggles to put the nightmare behind her. But the mysterious creatures that live in the ocean aren't about to let her forget. After meeting Bastin - a strange boy with silver hair and black eyes - on a secluded dock, Edith learns about the war raging undersea to end human existence. A war that Edith, unwittingly, has become the key to winning. In a world where death is an ever-present shadow and motives are as dark as the bottom of the ocean, Edith must decide if her life is worth risking for a love that can't survive past the shore.