This Gilded Abyss

In This Gilded Abyss by Rebecca Thorne, Sergeant Nix Marr grapples with her haunting past as she reluctantly agrees to join her ex, Princess Kessandra, on a perilous mission to the abyssal city of Fall. Initially resistant to Kessandra's request for help with a massacre investigation, Nix soon discovers that their journey is far more dangerous than anticipated, complicated by a spreading disease that incites violent behavior. As tensions rise aboard the luxurious submersible and secrets unravel, Nix must navigate her tumultuous feelings for Kessandra while fighting to survive against an unseen threat.