The distant and unloved colony world of Russalka has no land, only the raging sea. No clear skies, only the endless storm clouds. Beneath the waves, the people live in pressurised environments and take what they need from the boundless ocean. It is a hard life, but it is theirs and they fought a war against Earth to protect it. But wars leave wounds that never quite heal, and secrets that never quite lie silent. Katya Kuriakova doesn’t care much about ancient history like that, though. She is making her first submarine voyage as crew; the first nice, simple journey of what she expects to be a nice, simple career. There is nothing nice and simple about the deep black waters of Russalka, however; soon she will encounter pirates and war criminals, see death and tragedy at first hand, and realise that her world’s future lies on the narrowest of knife edges. For in the crushing depths lies a sleeping monster, an abomination of unknown origin, and when it wakes, it will seek out and kill every single person on the planet

The battle lines have been drawn. The people of Russalka turn upon one another in a ruthless and unwavering civil war even while their world sickens and the deep black ocean is stained red with their blood. As the young civilisation weakens, its vitality fuelling the opposing militaries at the cost of all else, the war drums beat louder and louder. Katya Kuriakova knows it cannot last. Both sides are exhausted – it can only be a matter of days or weeks before they finally call a truce and negotiate. But the days and weeks pass, the death toll mounts, and still the enemy will not talk. Then a figure from the tainted past returns to make her an offer she cannot lightly refuse – a plan to stop the war. But to do it she will have to turn her back on everything she has believed in, everything she has ever fought for, to make sacrifices greater even than laying down her own life. To save Russalka, she must become its greatest enemy