From J.M. Lee, a bestselling phenomenon in Korea, comes a haunting and mind-bending novel about the revolutionary possibilities of AI and the infinite mysteries of what it means to be human.

In the virtual city of Alegria, fantasies are made real, innumerable lifetimes are lived, and even death itself is a survivable experience. An escape from reality that changed the landscape of artificial intelligence, it is home to more than one hundred million people. Though it's been six years since Alegria's creator--revolutionary tech genius KC Kim--died of cancer, his legacy is alive in the pinnacle of KC's genius: an AI named Allen who surges with KC's memories.

As hard as KC's widow, Minju, and her new husband, Junmo, try to move on, Minju can't shake the unnerving feeling that somehow, from somewhere, KC is watching. She sees a stranger who bears an uncanny resemblance to him. A pair of KC's custom-made shoes arrive at her doorstep. And someone has booked a Tokyo hotel room where she and KC shared happier times. Certain of nothing except KC's mad innovation, Minju can only imagine what he is accomplishing without even existing.

If KC is reaching out from an infinity of memories, what are his plans for Minju and Junmo, and how can they hope to escape KC's all-seeing grasp? And whose plans are they, really? The possibilities are frightening.