Fever Series by Karen Marie Moning

MacKayla Lane's life is good. She has great friends, a decent job, and a car that breaks down only every other week or so. In other words, she's your perfectly ordinary twenty-first-century woman. Or so she thinks...until something extraordinary happens.

When her sister is murdered, leaving a single clue to her death-a cryptic message on Mac's cell phone-Mac journeys to Ireland in search of answers. The quest to find her sister's killer draws her into a shadowy realm where nothing is as it seems, where good and evil wear the same treacherously seductive mask. She is soon faced with an even greater challenge: staying alive long enough to learn how to handle a power she had no idea she possessed-a gift that allows her to see beyond the world of man, into the dangerous realm of the Fae...

As Mac delves deeper into the mystery of her sister's death, her every move is shadowed by the dark, mysterious Jericho, a man with no past and only mockery for a future. As she begins to close in on the truth, the ruthless Vlane-an alpha Fae who makes sex an addiction for human women-closes in on her. And as the boundary between worlds begins to crumble, Mac's true mission becomes clear: find the elusive Sinsar Dubh before someone else claims the all-powerful Dark Book-because whoever gets to it first holds nothing less than complete control of the very fabric of both worlds in their hands...

I used to think my sister and I were just two nice southern girls who'd get married in a few years and settle down to a quiet life. Then I discovered that Alina and I descend, not from good wholesome southern stock, but from an ancient Celtic bloodline of powerful sidhe -- seers, people, who can see the Fae. Not only can I see the terrifying otherworldly race, but I can sense the sacred Fae relics that hold the deadliest of their magic.

When my sister was found dead in a trash-filled alley in Dublin, I came over to get answers. Now all I want is revenge. And after everything I've learned about myself, I know I have the power to get it...

MacKayla Lane's ordinary life underwent a complete makeover when she landed on Ireland's shores and was plunged into a world of deadly sorcery and ancient secrets.

In her fight to stay alive, Mac must find the Sinsar Dubh -- a million-year-old book of the blackest magic imaginable, which holds the key to power over both the worlds of the Fae and of Man. Pursued by Fae assassins, surrounded by mysterious figures she knows she cannot trust, Mac finds herself torn between two deadly and irresistible men: V'lane, the insatiable Fae who can turn sensual arousal into an obsession for any woman, and the ever-inscrutable Jericho Barrons, a man as alluring as he is mysterious.

For centuries the shadowy realm of the Fae has coexisted with that of humans. Now the walls between the two are coming down, and Mac is the only thing that stands between them...

Mac's quest for the Sinsar Dubh takes her into the mean, shape-shifting streets of Dublin, with a suspicious cop on her tail. Forced into a dangerous triangle of alliance with V'lane, an insatiable Fae prince of lethally erotic tastes, and Jericho Barrons, a man of primal desires and untold secrets, Mac is soon locked in a battle for her body, mind, and soul.

As All Hallows Eve approaches and the city descends into chaos, as a shocking truth about the Dark Book is uncovered, not even Mac can prevent a deadly race of immortals from shattering the walls between worlds with devastating consequences.

They may have stolen my past, but I’ll never let them take my future.
When the walls between Man and Fae come crashing down, freeing the insatiable, immortal Unseelie from their icy prison, MacKayla Lane is caught in a deadly trap. Captured by the Fae Lord Master, she is left with no memory of who or what she is: the only sidhe-seer alive who can track the Sinsar Dubh, a book of arcane black magic that holds the key to controlling both worlds.
Clawing her way back from oblivion is only the first step Mac must take down a perilous path, from the battle-filled streets of Dublin to the treacherous politics of an ancient, secret sect, through the tangled lies of men who claim to be her allies into the illusory world of the Fae themselves, where nothing is as it seems—and Mac is forced to face a soul-shattering truth.
Who do you trust when you can’t even trust yourself?

“Evil is a completely different creature, Mac. Evil is bad that believes it’s good.”

MacKayla Lane was just a child when she and her sister, Alina, were given up for adoption and banished from Ireland forever.
Twenty years later, Alina is dead and Mac has returned to the country that expelled them to hunt her sister’s murderer. But after discovering that she descends from a bloodline both gifted and cursed, Mac is plunged into a secret history: an ancient conflict between humans and immortals who have lived concealed among us for thousands of years.
What follows is a shocking chain of events with devastating consequences, and now Mac struggles to cope with grief while continuing her mission to acquire and control the Sinsar Dubh—a book of dark, forbidden magic scribed by the mythical Unseelie King, containing the power to create and destroy worlds.
In an epic battle between humans and Fae, the hunter becomes the hunted when the Sinsar Dubh turns on Mac and begins mowing a deadly path through those she loves.
Who can she turn to? Who can she trust? Who is the woman haunting her dreams? More important, who is Mac herself and what is the destiny she glimpses in the black and crimson designs of an ancient tarot card?

From the luxury of the Lord Master’s penthouse to the sordid depths of an Unseelie nightclub, from the erotic bed of her lover to the terrifying bed of the Unseelie King, Mac’s journey will force her to face the truth of her exile, and to make a choice that will either save the world . . . or destroy it.