Solomon's Ring - Demon Powers, #1

The Apocalypse Is Coming. As a mysterious figure plots to end the world, a young woman finds herself contending with an unusual personal problem. Demonic possession. While Brooklyn struggles for control of herself and the strange powers growing within, she runs afoul of both police and the leaders of a supernatural community she never knew existed. Trapped in the tangled politics of this new world, where the good guys want her executed and the very worst would recruit her as an ally, Brooklyn soon discovers power-hungry humans are far deadlier than most demons. Fighting for the freedom to choose her own fate, Brooklyn draws the eye of an ancient evil that will stop at nothing to bring her under its control.
With her parents and young nephew suddenly threatened, can she find a way to master the abilities she wields? Or will her family pay for her failure with their lives?