Police anti-corruption unit AC12 return for another thrilling investigation. Sergeant Danny Waldron and his armed response team shoot dead a hardened criminal, but soon cracks appear in their story. What are they hiding?
After the shooting at the drugs house, DC Kate Fleming uses her undercover role to increase the pressure on Danny Waldron's armed response unit. Meanwhile a previous AC12 investigation comes under legal scrutiny.
DS Steve Arnott believes there is a dark secret in Danny Waldron's past. But while DI Cottan is commended for cracking the Waldron case, the spotlight falls on Arnott's questionable conduct in a previous enquiry.