Sergeant Nix Marr has spent the last four years trying to leave the past where it belongs: buried at the bottom of the ocean, deep within the mines that drowned her best friend. So, when her royal flame, Kessandra, comes begging for her help investigating a massacre, Nix refuses. Vehemently. But Kessandra always gets what she wants. Aboard a luxurious submersible, Kess and Nix are drawn closer together the deeper they dive. But as dangerous as their attraction is, it's not the greatest threat onboard: a deadly illness has emerged that drives its victims to extreme violence. When another royal is brutally murdered, it becomes apparent the disease has spread-and no one on the submersible is safe. Suddenly, survival hinges on trusting each other, which would be a hell of a lot easier if Kessandra didn't keep lying. Injured, fighting for their lives, Nix has to decide if she can trust Kessandra again... and what she'll lose if she does.