As the daughter of a London crime boss, PC Philomena McCarthy walks a thin blue line keeping the two sides of her complicated life apart.

On patrol one night she discovers a child in pyjamas, wandering alone. Taking Daisy home, Phil uncovers the aftermath of a deadly home invasion, as three miles away a prominent jeweller is found strapped to an explosive in his ransacked store. The crimes are linked, and all the evidence points to Phil's father as the mastermind.

Phil's two worlds are colliding, trapping her in the middle of a vicious gang war that will threaten her career and everyone she loves. Who can she trust - the badge or her own blood?