Of Curses and Shadows. Wardens of Estralia, #2

The seal beneath the Forbidden City has broken-and something worse than death is slipping free. When ancient protections fail on the island of Varnrin, unnatural creatures spill into the palace and shadows that once obeyed begin to hunt. A force older than the Wraith Queen has awakened beneath the city's sacred tree-one that devours memory, twists magic, and is no longer bound. Vivienne Valeran and her allies must return to Varnrin to uncover the truth before what's been unleashed spreads across the threshold between worlds.
But someone inside the palace is helping it. Artefacts are being stolen. Defenders are disappearing. And a power once thought sealed in myth is moving again. If the source of the corruption isn't stopped, it won't just take Varnrin. It will take everything.