Mortal Curse by Tia Didmon

A shadow. A shifter. A curse.

When a reaper attack thrusts Dannika into the shadow shifter world and her transition results in her imprisonment, she turns to Raine, the sexy shadow who saved her.
As her attraction to Raine mounts, and dissension in the shadow shifter clan increases, she learns that being the only woman to survive the transition isn’t her only secret. Her new abilities come with a price, and if she doesn’t curb her killer instincts, she will end up as loathsome as the creature who attacker her.