Samantha Cullen and Hope Nemera are like sisters. But sisters keep secrets, and lately, they’ve grown distant, especially about the big Seattle tech company where they work. A lawyer for Hope’s family reveals how much they’ve been hiding from one another when he informs Samantha that Hope took her own life—leaving behind a single envelope addressed to her.

Samantha is shocked. They’d had lunch the day before. Yes, Hope ranted about the dangers of the company’s soon-to-be-released, touted AI product, the AssistBot, but her obsession with the ethical consequences of AI infiltrating the world wasn’t new. According to Hope, the AssistBot was laying the groundwork for a digital Handmaid’s Tale, but Samantha always thought she was overreacting. 

As Samantha searches for answers, she comes to believe that Hope’s death wasn’t a suicide. She takes risk after risk to uncover the truth, discovering that Hope’s fears and paranoia were legitimate, putting herself and her four-year daughter’s life in jeopardy as the killers close in to silence her.