On a newly settled world, a thirteen-year-old finds a pair of gravity boots and becomes the wall-walking thief known as Wally.

But aliens land on their world and upset the delicate colony. Some humans, led by a mysterious policy known as the Dark Colony plan, seek to goad the aliens into a war against Earth. An ambassador from Earth arrives to prevent that and find the truth about the Dark Colonies. Meanwhile, Wally's thieving friends use the chaos to make a play for their independence. When the aliens encounter Wally, they see him as a gravitational anomaly and choose him as humanity's representative. Suddenly everyone's plans depend on him.

If the Dark Colony plan activates, Wally and his friends are doomed. If negotiations fail, the aliens will destroy the colony and wage war with Earth. Wally needs to sneak, jump, and think his way through all of this, when all he wanted was three meals a day.