Line of Duty (2012 TV Series) - Season 4 - Episode 2

Now on BBC One, the 6-episode fourth season follows the investigation of DCI Roz Huntley. Under pressure to catch a serial killer, Huntley is suspected of tampering with evidence to secure a conviction. When a forensic investigator goes missing, AC-12 faces its most politically connected opponent yet, leading to a battle of wits that leaves Steve Arnott severely injured.