Over the course of the series the overarching theme is the criminal gang and their associates- associates within the police force and other areas of the community.
In each series there is a crime that is then covered up by the gang in league with members of the force.
This often involves blackmailing/framing someone else for the crime.
Who is being blackmailed/framed in this series?
Series 1
The Moss Heath murders related to a drug operation.
Gates blackmailed over Jackie's murder.
Tommy Hunter makes a deal for information over the fabricated terrorist plot and enters witness protection
Series 2
Tommy Hunter's murder - Denton takes the fall.
Caddy claimed to be Cole the dead vice cop.
Series 3
Historic child abuse cover up
Steve framed as the caddy.
In this series I think Nick is connected to the criminal gang- handling their business/money laundering or something.
Roz is being blackmailed due to Nick's connection.
Michael Farmer is being framed.
Who are the ring leaders currently?
Tommy Hunter was killed by the gang- who took over ,is that Lakewell?
Who's the 2 faced bastard within the force? -Hilton or possibly Osborne?
The Mason's keeps cropping up so perhaps it will emerge is that Lakewell, the 2FB , other elements involved are in The Masons.
Hilton was involved in the Hunter deal as was Osborne who was head of counter terrorism.