For DCI Eleanor Blackwell, every crime is a map waiting to be read. But when a priceless Roman artifact vanishes from Hadrian's Wall, replaced by a single, chilling rune, she finds herself facing a landscape of violence she's never charted.

The symbolic thefts soon turn to ritualistic murder. A celebrated historian is found dead, a Norse curse tablet on his chest and Celtic poison in his veins. Ellie and her partner, DI Ben Carter, are plunged into a conspiracy rooted in the nation's oldest wounds. A shadowy cult, the Wolves of Fenris, has risen, led by a ghost-like military commander who believes history is a cage—and he has the key to unlock it.

Following a trail of cryptic riddles and ancient symbols, Ellie uncovers their terrifying endgame: to assassinate a public figure and, in the ensuing chaos, destroy the Domesday Book, the nation's founding document. To stop a killer who thinks in centuries, Ellie must abandon her straight lines and learn to read the primal map of chaos... before the Wolf King unleashes Ragnarök on the modern world.