Rowan Black and the City Beneath the Grave. The Rowan Black Monster Files

Rowan Black has survived haunted houses, cursed crowns, and monsters that should never have been born. But beneath the oldest graveyard in Saint Oryn, something worse is waking. When graves split open and dead things crawl from sealed tombs, Rowan is pulled into a hidden world beneath the earth-a forgotten dead city of bone doors, cursed catacombs, underground rivers, and ancient grave magic. The deeper she goes, the more she realizes the city was not built for the dead.
It was built to imprison something. With Elias Vale at her side, Rowan must hunt through crypts, battle grave-born monsters, uncover forbidden relics, and face a terrifying power controlling the dead city from the shadows. But every secret buried beneath Saint Oryn points back to Rowan's bloodline, her growing power, and a truth someone tried to keep dead forever. As the grave-magic army rises, Rowan must choose between fear and courage, love and sacrifice, survival and destiny.
To save the living, she must enter the city beneath the grave-and defeat the darkness before it turns the world above into a kingdom of the dead. But some prisons are not meant to stay closed. And something ancient is about to escape.