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.

After spotting Tommy Lee Royce, Catherine is determined to find him and comes close to busting the kidnapping plot in the process. Kevin, who is overcome with guilt at seeing Nevison's despair, confesses everything to his shocked wife Jenny, who urges him not to take anymore money from Ashley. However, Kevin is reluctant to say no to money when they are in desperate need of it. Catherine becomes distressed when her ex-husband Richard continues with his refusal to accept Ryan.

The valley is rocked by the sudden, unprovoked murder of young police officer Kirsten McAskill, while Ashley and Lewis panic that Tommy Lee Royce's actions will lead to them being exposed. Catherine begins seeing her dead daughter as she struggles to come to terms with Kirsten's death, and reveals to Clare that she blames herself. Nevison's wife Helen urges him to involve the police in finding Ann, but he refuses, believing Ann is in too much danger.

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.

Catherine sinks into a deep depression as she learns that Tommy is still at large. The net finally closes in on Kevin.

Things get tense at Catherine's birthday party when a drunk Daniel reveals a different version of past events with Becky. Catherine's fears grow when she learns that Tommy has been spending time with Ryan.