Set in rain-soaked Liverpool, 1952, forensic detective William "Silas" Walker investigates the ritualistic murder of archaeology student Chloe Evans, who is found clutching a forged Mesopotamian cylinder seal in Princess Park. As Silas follows a trail of ancient forgeries, rare pollen from Iraq, and hallucinogenic toxins, the case entangles his own family history-particularly his sister Sarah's past involvement with wealthy antiquities collector Alistair Finch. With the help of his loyal partner Harry Coleman and pathologist Sarah Jones, Silas uncovers a deadly conspiracy.

Finch and his fanatical forger Milo Varga are using ritualistic killings to authenticate black-market artifacts. The hunt escalates with a second victim and a chilling intrusion into Silas's personal sanctuary, culminating in a pre-dawn confrontation at Formby Pool. Through forensic precision, psychological insight, and a rediscovery of human compassion-embodied by his wife Carol-Silas breaks the killer's delusion, saves an innocent life, and brings the perpetrators to justice.

In the aftermath, his dream of modern forensic science takes shape with "Project Thread," and Silas finds peace not just in solving the case, but in the quiet rituals of home and the belief that "there are no coincidences-only choices.