When the Qhan of Kil'Dur dies by the hand of a fanatical cultist, her mate unleashes a monstrous species upon Earth. Calla Shepherd is the eighteen-year-old girl who holds the key to stopping it. All she cares about is keeping her loved ones alive as she fends off bloodthirsty monsters from two worlds. To stave off the carnage, she teams up with a group of rebels planning their escape from town, but when a surprise confrontation forces Shepherd to face what she is, she's torn between saving the humans who shunned her from birth and the aliens seeking to weaponize her... What will the Leaven choose?