In a land where light deceives and darkness whispers, Cait Reagan’s fight to save her sister will awaken powers—and enemies—she never saw coming. Cait Reagan is bound for Ireland, but her mission to save her sister Aoife is imperiled from the start. Even as Cait struggles with her feelings for both Elizabeth and Nastasia, she discovers the Light Fae, once symbols of benevolence, have grown twisted and cruel. The Emerald Isle feels more like a trap than a haven. Along the way, Maggie, an Army Medic caught in the chaos of Cait and Nastasia’s escape from Boston, becomes an unwilling hostage—yet something within her suggests she may hold the key to the battles ahead. Meanwhile, Doyle undergoes disturbing changes, her once-innocuous cravings turning sinister, leaving the group uneasy. Then there's Rowan, the ancient and enigmatic vampire believed to be the first of their kind, whose motives are as inscrutable as they are unhinged. But the most alarming transformation lies within Cait herself. A dark power seems to take hold, driving her to increasingly ruthless actions. Her companions, though loyal, fear the Cait they knew is slipping away, to be replaced by something far more dangerous. Haunted by an eerie echo of her own voice, whispering truths she cannot yet face, Cait must navigate her unraveling self as the lines between ally and enemy blur beyond recognition. Dark, gripping, and steeped in supernatural peril, Dark Sisters weaves a tale of light shrouded in shadow. Cait’s struggle to save her sister may cost her everything—including herself. And as the mist clears, she finds herself facing a foe she never expected.