The Eighth Day: The Morrigan's curse

"The battle between Kin and Transitioners that's been brewing for centuries has finally come to a head. The sinister Kin have captured Evangeline's younger sister, Addie, a descendant of Merlin whose presence will allow them to reverse the Eighth Day Spell and free themselves ... She's been helping the Kin because they value the strength of her magic--something Evangeline never did ... Meanwhile, Riley, Evangeline, and Jax craft a plan to rescue Addie from her captors. But the Kin's unstoppable magic, and a rebellious Addie, force Riley to reconsider whether saving Addie is worth sacrificing everyone who lives in the seven-day week."--Provided by publisher.