8 years ago, Kira swan was diagnosed with a very rare disease, no one could figure what it was, so they named it the X-syndrome, what makes it so rare? Kira is the only who has had it. Kira lives as a normal girl in Forks, Washington with her dad Charlie, well almost normal but when her twin sister Bella moves from Florida, she attracts the attention of a certain family. while her sister falls for one of them, Kira's sickness starts to leave her with questions that only a certain vampire can answer. which vampire? read to find out in book one of the Immunity series