Catherine Cawood is a sergeant in a small town in West Yorkshire, riddled with a drug culture that seems impossible to tackle. Kevin Weatherill is an accountant in a large company run by his late father's best friend, Nevison. When Nevison refuses to pay Kevin's daughter's school fees, which Kevin believes Nevison owes him, Kevin orchestrates a kidnapping plot with local thugs Ashley Cowgill and Tommy Lee Royce against Nevison's daughter, Ann. Only for the whole thing to backfire. Sergeant Catherine Cawood lives with her recovering heroin addict sister and brings up her eight-year-old grandson, Ryan. Whilst visiting Ryan's teacher regarding his behavioural problems, Catherine reveals her daughter was raped by Tommy Lee Royce and so committed suicide shortly after giving birth to Ryan, leaving Catherine to bring Ryan up alone. The episode ends with a very anxious Kevin entering Catherine's West Yorkshire police station to report the kidnapping. But he changes his mind at the last minute.
Catherine is still haunted by Kirsten's death, and her depression spurs her on her quest to find Tommy Lee Royce. Realising that the net is closing in on them, Ashley orders Tommy to 'dispose' of Ann, but instead he holds her prisoner in his mother's cellar. Following her hunch, Catherine manages to speak with Helen face to face, and is stunned when Helen admits everything. With all falling into place, Catherine's heroic actions are shattered when Royce murderously assaults her, leaving both Ann and Catherine to fight for their lives.
Eighteen months have passed, and Catherine is spinning plates at work and at home, where Ryan approaches his tenth birthday. Tommy, serving a life sentence in a high-security prison, finds a way of keeping a watchful eye over Ryan from behind bars, while Catherine becomes a murder suspect after finding a dead body.
