Matthew Taylor, a 16-year-old school boy was brutally murdered in the quiet Lake District. Five years later the accused is found not guilty and released from prison, but who did kill him?

As Sally begins a confident return to work, the police question Anna Stamp - what is she hiding, and more importantly what are Matthew's parents covering up? Karen grows increasingly paranoid over Sally and Sam.

As Sally and Sam grow closer, the police investigation turns to Gary Walker, but what is his connection? Meanwhile, Bethany's link to Matthew comes to light as Karen admits a damning secret.

With Karen still in police custody, Bethany takes matters into her own hands - making a crucial discovery and forcing a confession. Braithwaite and his team continue their search for more evidence. Sam and Sally come to a decision.