A murder without motive.
A downtown bombing.
The sins of the past revisited.
DI Nathaniel Caslin is heading up a specialist unit, an opportunity to make a real difference.
Little does he know, decisions taken decades previously are about to threaten all that he holds dear.
Gangland tensions are on the rise as an uneasy peace is fractured in spectacular fashion.
Two warring factions are lining up to unseat the other.
Old adversaries rekindle their passion to exact reve.