Born on Mars, sixteen-year-old Arabella Ashby enjoys many more freedoms than most girls her age, tramping around the desert with her older brother. But that liberty is not to last. Finding Mars much too unladylike for her daughters, Arabella's mother takes the girls back to London, where they're sure to find suitable husbands among the ton.Weighed down by Earth's gravity--and her own unhappiness--Arabella dearly misses her father and their shared passion for automata. When she learns of his death, she also uncovers her cousin's devious plot to travel to Mars, murder her brother, and claim the family inheritance for himself.To foil his dastardly plans, Arabella disguises herself as a boy to gain employment on an airship to Mars. Though she is valued by the captain for her talent with the automaton navigator he invented, she must survive French privateers, mutiny, and her own unmasking, only to reach a Mars embroiled in rebellion . . .