Hereditary Magic. The Gatekeeper's Curse, #1

Ilsa Lynn has made it her life's goal to avoid the curse that binds her family to serve the Summer Court of Faerie. With her magically talented twin sister given the role of Gatekeeper, Ilsa is content to hide under the radar amongst the regular humans. At least until a mysterious spell book falls into her possession, granting Ilsa with a sudden and inconvenient affinity with the dead, and dangerous magic that paints a neon target on her head.
With her family's questionable past quite literally refusing to stay buried, the last thing Ilsa needs is an untrustworthy self-proclaimed faerie bodyguard, even if he does come with a deadly skillset of his own. Dealing with zombies and fae assassins would be difficult enough on its own, but now someone's out to frame her for murder, too. While dodging enemies at every corner, Ilsa must get a handle on her new powers before the armies of Faerie invade Earth.
She might just be in over her head.