Willa stayed in her bed when a spaceship landed near her home and the interstellar invaders she calls Ironhides abducted children from her neighborhood--her sister among them. Now, along with her best friend, Isaiah, Willa will risk a journey to the Earth colony on the planet Nexpernon to bring her sister home. He has no name, only a rank, Fifth. He's been kept in the dark about most details of his mission. But a few directives hum in his mind: take all essence of joy the humans have in them, and then leave them where they fall. His job is to protect his Commander, and to ensure the portal his kind uses to get to Earth remains a secret forever. Thrown together in a vehement, unfamiliar situation, Willa and Fifth should hate and fear each other. But when Willa kills his Commander and Fifth deserts his unit, their survival depends on trusting one another. And their ability to work together might be the only hope to restore joy to all of humanity.