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.
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.
Catherine arrives home with Ilinka, an emaciated Croatian woman who has been rescued after being trafficked and enslaved for the past four years. Meanwhile, John's panic over Vicky's threat spills out into his home life.
Tommy urges Frances to go further with her attempts at making Catherine's life a misery, and a therapist tries to understand why Catherine attended Tommy Lee Royce's mother's funeral. Meanwhile, John begins to sweat when a new body is discovered.
Sean becomes prime suspect when Leonie is raped, and the authorities believe he could be responsible for the string of murders Andy and the team have been investigating. Meanwhile, John has to think fast when he's asked why his number was on Vicky's phone, and a gift for Ryan on his tenth birthday reminds Catherine that danger may be closer than she thinks. Elsewhere, Daryl takes action when he is confronted by the three lads who have been bullying him.
Daniel suspects somebody at school might be responsible for Ryan's new-found interest in Tommy, and tries to explain that he wasn't really a dad to him, while, despite Sean protesting his innocence, Jodie and John receive permission to charge him with all of the murders. However, delight at the developments is tempered when another body is found in the early hours, and Daryl wakes a stunned Alison in the middle of the night and confesses to murder, leading to dramatic scenes at the breakfast table.
Catherine and Shaf call in at Far Sunderland farm to visit Alison and Daryl, but discover a scene of carnage when they enter the building, with Alison slumped on the dining table covered in blood having taken an overdose. Meanwhile, Andy and Jodie begin to suspect that the person who killed Vicky Fleming could be someone on the team and as the investigation heads towards a conclusion, John's torment increases, leading him to take drastic measures to avoid the consequences of his actions.
When Catherine discovers the remains of a murder victim, it bizarrely leads her straight back to Tommy Lee Royce.
Catherine learns of a painful betrayal close to home, and Faisal comes under increasing pressure from all sides.
Catherine confronts Clare and presents Ryan with an ultimatum. Faisal and Joanna hatch a plan that takes an unexpected turn.
As Tommy’s big day approaches, Catherine becomes suspicious, and Ryan finds a new way to defy her.
Catherine races to protect her family as a murder investigation begins.
Scores are settled for good on Catherine’s final shift, and Ryan faces a moral dilemma.
Catch up with series one of this thrilling crime drama.
