The quaint spa town of Harrogate, in the north of England, isn’t supposed to be dangerous. But DCI Rosie Marks knows better.

When a teenage drug runner is found stabbed in a quiet North Yorkshire street, DCI Rosie Marks is drawn into a brutal turf war that’s anything but rural. At the helm of the violence is Manchester crime boss Brian Hazell — a ruthless operator with a reputation for staying one step ahead of the law.

As Rosie and her elite unit, Operation Caterpillar, push back against the growing threat of county lines drug gangs, the battle turns personal. Hazell isn’t just expanding his empire — he’s sending a message. And Rosie is listening.

With her team stretched thin, her daughter needing extra care, and a suspected leak inside her own station, Rosie must risk everything to stop Hazell — before more innocent lives are destroyed.

Fast-paced, gritty, and utterly gripping, County Lines introduces DCI Rosie Marks — a fierce northern detective fighting crime where you least expect it