The Ship, its towering structures perched upon the foundation of a massive asteroid, was launched as the last gasp of a dying Earth. The Mission—seed the universe with one billion colonists who wait in cryostorage for their chance at a new homeworld. Five thousand years into a journey that was supposed to take one hundred, both the Ship and its society are starting to fray. Fifteen-year-old Zax has trouble fitting in with the other cadets, but earns scores which place him near the top of the all-important Leaderboard. He's already on the cusp of attaining his dream and gaining entrance to the Flight Academy when he catches the eye of the second most powerful officer in the Crew—the Fight Boss. Winning the Boss as a mentor will guarantee Zax a top position, unless the startling discovery he makes along the way destroys not only his career, but also the Ship itself.

Zax should be training to pilot a fighter with his best friend Kalare, but instead he defied the Flight Boss and his career is in the toilet. His new job managing sewage in Waste Systems may be disgusting and boring, but it allows him time to become adept with his Plug and study the Ship's infrastructure. It also exposes Zax to civilians for the first time in his life as he works closely with Imair and befriends eight-year-old Nolly. A year-long period of civilian unrest, which started when Zax revealed his discovery of an unknown spacecraft from Earth, finally erupts into full-blown revolution. He is thrust into the middle of the rebellion, alongside longtime friends and enemies, where his special talents make the difference between life and death. Zax eventually puts himself into a position where he can rocket back to the top of the Leaderboard and restore his career—at a price.

Life on the Ship has changed, and for Zax it means a return to the top. The Pilot Academy finally beckons and Zax battles for position against a competitor who brings a fascinating advantage. Meanwhile, his friendship with Kalare remains strained as he refuses to drop his suspicions about the Flight Boss and the officer's knowledge of the mysterious humans. As the Ship travels back towards Earth, the Crew visit a series of previously established colonies and discover startling information about their colonists. Zax eventually gains a new friend who unlocks the past, but the knowledge leads Zax to put his faith in someone who could be a powerful ally—or an even more dangerous foe.

Adan is ready to leave Earth behind. He successfully transformed his massive asteroid into an amazing spaceship, but faces an even larger challenge as he tries to negotiate the repercussions of the many deals and compromises that were required along the way. The choices he makes will not only impact those people who remain behind, but will also determine how the society onboard his vessel survives far into the future. Five thousand years after it first left Earth, the Ship is racing back in search of the mysterious humans its Crew has battled repeatedly. The Flight Boss is navigating an uneasy partnership with the civilian president as the Ship's condition degrades rapidly, but puts his trust in Kalare to prepare their pilots for one final battle to reclaim humanity’s homeworld.

With the battle for Earth over, our heroes are forced to deal with the repercussions of its outcome. They enlist their closest allies to take back the Ship from enemies both new and old, and along the way they discover a most unexpected source of help.