По долгу службы Season 4 Episode 2

A dismembered body is discovered, and worries grow when DCI Roz Huntley fails to report for duty. AC-12 crank up their investigation into Operation Trapdoor, concerned that Michael Farmer will go to jail for crimes he didn't commit. With suspicions that Roz may have withheld crucial evidence, a new DCI is drafted in to run Operation Trapdoor. Kate makes progress in her undercover role, but AC-12's investigation falters when they realise that their main informant, forensic investigator Tim Ifield, has also gone missing.