The double murder of a married couple in a small Washington town draws FBI forensic linguist Raisa Susanto into an investigation that mirrors a decades-old crime. Twenty-five years ago--to the day--Alex Parker murdered his parents, then took his own life, leaving behind a note admitting everything.

Raisa, paired with forensic psychologist Callum Kilkenny, uses her skills to read between the lines. Especially now that paranoid postings on a conspiracy thread suggest that Alex was a victim himself--theories that have piqued the interest of a perceptive content moderator and a true-crime podcaster eager for a big break.

As old and new crimes converge, messages from the living and the confessions of the dead take on new meaning for Raisa. Something more sinister than a copycat crime is at play, and plundering the darkest corners of a killer's mind leaves her vulnerable to a deadly twist even she never saw coming.