In the tumultuous aftermath of the Qhan of Kil'Dur's assassination by a zealous cult, a devastating alien species descends upon Earth, unleashed by the Qhan's bereaved mate. Amidst this chaos stands Calla Shepherd, an 18-year-old misfit with an unassuming power that holds the key to mankind's salvation.

Calla's only priority is to protect her loved ones from the ruthless onslaught of the alien creatures, yet her path converges with a group of brave rebels planning a daring escape from her besieged town. As this makeshift family battles against the bloodcurdling horrors of two worlds, an unexpected showdown forces Calla to grapple with her concealed identity.

Now caught in a harrowing moral dilemma, Calla must choose between saving the human race that ostracized her since birth, and the extraterrestrial beings eager to exploit her extraordinary abilities. As the fate of two worlds hangs in the balance, which path will the Leaven choose?