With exclusive access to Humberside CID, this series reveals the meticulous work of detectives as they navigate their way through the twists and turns of an investigation, gathering the clues that could ultimately reveal the truth. In Grimsby, a vicious mass street brawl causes mayhem and leaves innocent victims with serious injuries in its wake - one person with a critical head wound. Police initially arrest three men but are then thrown into a desperate race against time to find their accomplices before one of them flees the UK to Romania.

A man is viciously attacked on his doorstep and although he fights off his aggressors he is left shaken and bloodied. Armed response police arrest four men found in nearby streets and the stakes are upped significantly when detectives recover an imitation police ID badge, a rental van and a knuckleduster, as well as other paraphernalia indicating this is a disturbing and premeditated assault. With the gang of suspected attackers giving little away in their custody interviews, police face an uphill battle, and it's a race against time to prove they have the right men in custody