This Gilded Abyss

Sergeant Nix Marr is a damn good soldier, but she's desperate to leave her haunted past in the bioluminescent ocean, buried alongside old friends...and old flames. Unfortunately, even the icy ocean can't extinguish some fires. When Kessandra, everyone's favorite princess—and Nix's loathed ex—requests Nix's help investigating a massacre in the abyssal city of Fall, Nix refuses. Vehemently.

But Kessandra always gets what she wants.

Consigned as Kessandra's bodyguard, Nix grudgingly boards a luxurious submersible that offers the only transportation to Fall. It's frustrating, irritating, how quickly Nix and Kess fall back in sync—much as she tries to fight, Nix can't deny their spark. But Kessandra wasn't truthful—surprise, surprise—and Nix quickly realizes their "investigation" isn't about the massacre, but rather what caused it: an illness that incites its victims into a violent craze.

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 this time.