A story of romance, rebellion and the stars from New York Times bestselling author Claudia Gray.

Noemi is a young and fearless soldier of Genesis, a colony planet of a dying Earth. But the citizens of Genesis are rising up they know that Earth's settlers will only destroy this planet the way they destroyed their own. And so a terrible war has begun.

When Noemi meets Abel, one of Earth's robotic mech warriors, she realizes that Abel himself may provide the key to Genesis' salvation. Abel is bound by his programming to obey her even though her plan could result in his destruction. But Abel is no ordinary mech. He's a unique prototype, one with greater intelligence, skill and strength than any other. More than that, he has begun to develop emotions, a personality and even dreams. Noemi begins to realise that if Abel is less than human, he is more than a machine. If she destroys him, is it murder? And can a cold-blooded murder be redeemed by the protection of a world?

Stranded together in space, they go on a whirlwind adventure through Earth's various colony worlds, alongside the countless Vagabonds who have given up planetary life altogether and sail forever between the stars.

Each step brings them closer both to each other and to the terrible decision Noemi will have to make about her world's fate, and Abel's.