City Central - Season 3 Episode 6 Nutcase.
Overview: Alfie Stokes is a sadistic, underworld-type who now claims to have found God, and he's DI Carter's star witness in the prosecution of Barry Roberts, a local drug dealer. But then former sergeant Yvonne Mackey turns up with some difficult question… Back at Christmas Street, Nick is livid that Sgt Dobson forgot to enter him for his sergeant's exams and threatens to take action.