In this first book in the Rift trilogy-a fast-paced action-adventure and an enthralling mix of speculative fiction and military thriller-a young soldier comes to question the monsters she's trained to fight against ... and the monsters she fights for

Seventeen-year-old Ryn Whittaker is a Citadel: an elite, enhanced soldier specially chosen to guard the Rift, a mysterious and dangerous portal to alternate Earths that scientists cannot control or close. Trained from the age of fourteen, Ryn can run faster, jump farther, and fight better than a Navy SEAL-which is good when you're not sure if a laser-wielding Neanderthal or an ax-wielding Viking is trying to make it through the Rift and into your world.

But Ryn's military conditioning and education have not prepared her for a boy who crosses through-a confused young man, seemingly lost and alone. Though there's an immediate physical attraction, it's his intelligence and curiosity that throw Ryn off-balance. The stranger asks disturbing questions about the Rift that Ryn herself has never considered-questions that lead her to wonder if everything about her life and what she's been told for so many years have been lies.

Are Rifts as dangerous as her leaders say? Should her people really try to close them ... or learn how to travel through them?