The wonders and chaos of AI converge in a powerful and thrilling novel about rewriting history, identity, love, and what it means to be human.

Graham Gooding is a leader at a tech start-up when his brilliant coworker—and work crush—Nessie Locke asks for help testing a new algorithm. Graham jumps at the chance to impress her, and to improve his floundering personal life. He soon discovers that the algo is more powerful than Nessie—or anyone—realizes. It was built to detect lies on the internet, but when Graham makes a small edit to Nessie’s online profile, hoping to see if the program will catch the lie, Nessie changes in real life. The algo can alter the real world. Now, so can Graham.

No one knows what Graham has done, except his boss, enigmatic tech guru David Warwick. Graham is racked with guilt, but Warwick thrills to the possibilities of what they can do next. This promises to be the innovation that will make Warwick a household name. Drawn by the power of the algo but terrified by its potential for chaos, Graham must decide what to do and whom to trust in a world where one true reality no longer exists.

As love, trust, memories, and what it means to be human begin to slip away, Graham and Nessie work together to restore the past—before it’s lost to the anarchy of a world without truth.