In her immaculate Silicon Valley home office, Merril believes in patterns and systems. But her life as a hotshot coder and AI expert falls apart when her younger sister Angie vanishes on her way home from class. After the police abandon their search, Merril gathers the digital material her sister left behind — from texts and emails to online purchases and social media comments — and creates an AI composite. The virtual Angie is a comfort. Until it starts to reveal new details about the real Angie’s disappearance.