The city of Bulwark is aptly named: a walled city built to protect and preserve the people who managed to survive a series of great cataclysms, Bulwark was founded on a system where sacrifice is rewarded by the AI that runs the city. Over generations, an elite class has evolved from the descendants of those who gave up the most to found mankind's last stronghold, called the Sainted.

Saint Enita Malovis, long accustomed to luxury, feels the end of her life and decades of work as a bio-prosthetist approaching. The lone practitioner of her art, Enita is determined to preserve her legacy and decides to create a physical being, called Nix, filled with her knowledge and experience. In the midst of her project, a fellow Sainted is brutally murdered and the city AI inexplicably erases the event from its data. Soon, Enita and Nix are drawn into the growing war that could change everything between Bulwark's hidden underclass and the programs that impose and maintain order.

A complex, imaginative, and unforgettable novel, We Lived on the Horizon grapples with concepts as varied as the human desire for utopia, body horror, and what the future holds for humanity and machine alike.