How do you stop a dangerous outsider when the rules say you can’t kill him? Crane likes rules almost as much as she likes her knives. Rules give structure to her world. She can depend on rules to provide firm footing. Unlike, say, gravity. It takes a grav-walker like Crane to navigate the treacherous, unpredictable gravity zones that fill the city. Outsiders to the zones—the downies who think “down” means the ground—are all too likely to get themselves killed. Crane has been assigned the mission of escorting a downie to the mysterious Tower, and the mission rules give her regrettably little wiggle room to use her knives on him. Even though no one—especially not a downie—should get their hands on the secrets in the Tower. Crane always obeys the rules. But in the zones, rules are like gravity—all a matter of perspective.

When your life has a deadline, why play it safe? Grav-walker Jasper Pine has always known she’d die young. She makes a living hunting for salvage in the decaying, three-dimensional maze of the gravity zones, where any direction can be down and every leap could be your last. Even if her reckless lifestyle doesn’t kill her, the alien infection inside her will soon explode, and the resulting cataclysm of broken gravity could endanger the entire planet. She’ll die to prevent that from happening. Then an unexpected glimmer of hope appears and changes everything. A feral boy holds the key to her future, but he’s been captured by a ruthless militarized cult. Jasper will have to turn to the one person she should be avoiding, Ryan Latrans, a charming outsider who’s been sent into the zones to retrieve a sample of the alien infection for a powerful and unscrupulous man. With millions of lives at stake and time running out, can Jasper afford a leap of faith?

A shocking revelation. An explosive coup. It’s harder than ever to decide who to trust. Left reeling by the events of Zones Day, Jasper flees into the treacherous gravity zones with the outsider, Ryan, and the feral boy, Grammar, who will lead her to a location only he knows and a secret she hopes will save her life. But now they are being hunted by a fanatical army and a leader who will stop at nothing to get his revenge. At the heart of the zones the mysterious figure of the Guardian awaits them. She holds the key to the Tower and Jasper’s untested, dangerous cure. Jasper needs her help, but the Guardian has her own plans. Meanwhile Jasper grows closer to troubled ex-soldier Ryan Latrans, though she knows she shouldn’t. Her future is too uncertain, and Ryan is fighting demons of his own. If he can’t find a solution to his dilemma, Jasper will pay the price. Old hatreds, relationships, and nightmares from Jasper’s dark past are stirring up turmoil in her plans and her heart. How can she fight for hope when her past threatens to drown her?