When Michael O'Brien is refused entry to a lock-in and hit with an ashtray by the bouncer, Jamie Gunn, he drives home and returns with a shotgun. But after waiting in the dark to kill who assaulted him, he accidentally shoots and kills the man's best friend, Marvin Bradshaw.
After hearing about the assassination attempt on his nephew's life, Nottingham crime lord, Colin Gunn, puts out a £3,000 bounty on O'Brien. Dead or alive. With his brother David, the Gunn brothers are the real their city has been nicknamed 'Shottingham'. They run everything gang-related within a 5-mile radius of Bestwood. Their own personal gangsters paradise. Not a drug sold or weapon used without their say so.
Following the murder of Marvin Bradshaw, DCS Phil Davis, is put in charge of the case. Little does he know that there is a rat in his midst. A rat by the name of PC Charles Fletcher. A longtime friend of the Gunn brothers and sharing information with them in exchange for tailor-made suits.
After Fletcher supplies Colin with the names and address of people surrounding the murder of his nephew's friend, and later that night, a grenade is thrown through the window of the getaway drivers' parents, his girlfriend's house is petrol bombed and the accomplice takes a bullet to the arm in a single night of chaos.
After O'Brien is arrested for murder, he is out of Colin's reach. So, seeing no other option, he sends a small team to shoot up his parents' house. After giving statements to the police, they flee for Lincolnshire.
Colin lays out a plan to rob a city Jewelers, with the explicit order not to kill. But during the robbery, one of the thieves takes it personally when a woman, Marion Bates, steps between her daughter and his gun. He kills her and the goons flee the scene with next to nothing.
Colin Gunn beats the gunman half to death for the murder, then has him sent to a farm to be disposed of permanently.
John and Joan Stirling arrive at their new home in Lincolnshire. Despite police warnings of Colin Gunn's connections to the area, they insist they'll be safe.
After Peter Williams is arrested for the jewelry store robbery, Colin has his bent cop search the name of the other thief in exchange for a new suit.
After O'Brien is found guilty of murder, he hurls abuse at his victim's family and threatens Colin's life. Both have to be removed from the court.
Having spiral into a depression treated with drink and drugs over the murder of his friend, knowing it should have been him, Jamie Gunn dies of pneumonia. Colin breaks down upon hearing the news. As far as he is concerned, Jamie was murdered.
Colin calls a meeting with a plan. Kill O'Brien's parents.
Using friends who work for BT to get O'Brien's parents' new address, the Gunn's and their Bestwood Cartel head to the seaside for a week away. Armed with unused guns, PAYG sim-cards and a clean car, they're there for more than just sight-seeing.
After keeping a look out on O'Brien's parents for a couple of days, two hitmen strike the couple in their bungalow, killing both without mercy. The day after, the Gunn's return home for the funeral of their nephew, Jamie.
An unmarked cop car is robbed on the side of the road and PC Fletcher is put under surveillance, along with members of the Gunn family.
After tracking down the thief who robbed the unmarked police car, the police are able to put together enough evidence for arrest warrants when he turns super-snitch, and the Bestwood Cartel are arrested in a series of early dawn raids.
Colin and his Cartel are arrested, tried, and sentenced to life for their crimes.