The Siren's Covenant - A Dark Fantasy Novel of Ocean Magic, Blood Bonds, and the War Between Worlds #957451

Dr. Mira Kaine thought she understood the ocean. She was wrong.
When a 400-year-old shipwreck tears open scars she's had since birth, Mira discovers she's the last of the Anchors—humans born to bind an ancient treaty between the surface world and the depths below. The merfolk aren't the romantic creatures of legend. They're apex predators, imprisoned in the deep trenches for three thousand years by blood magic. And the treaty is breaking.
In 30 days, they'll be free.
Mira is offered an impossible choice: become the Anchor and lose her humanity forever, or let the treaty shatter and watch both worlds drown in war. But as she descends into the Tessellated Court—a kingdom built from shipwrecks and bone—she uncovers a darker truth. Both species have been lying. The treaty was never protection. It was chains.
Caught between a secret society hunting her bloodline and a mer prince who sees her as the key to conquest, Mira must make a choice that will reshape two worlds. But transformation has a price. Her bones are hollowing. Her blood glows in the dark. And with each breath underwater, she becomes less human and more something neither species has words for.
The covenant demands a sacrifice. The ocean demands blood. And Mira is running out of time to decide which world deserves to survive.