Only five years into his life sentence for killing his aunt and uncle, a crime committed when he discovered their abuse of his sister, John Mercer is released from prison.
Following the death of the head of a notorious crime family, Lenny visits his successor, the police mole Jude Cassidy.
Lenny is alerted to the recent arrival of a notorious Albanian gangster Tarek Sokoli. Sokoli wants to put down roots in his new homeland and that includes running drugs and prostitution rackets.
Calum has made Mercer some tea. Problem is that it's burned and totally lacking in nutritonal value. So off they go to the supermarket. Calum is amazed Mercer knows so much about cooking.
John Mercer's predecessor, Patrick Finch, has gone on a vigilante-style rampage, meting out his particular brand of justice against drug-dealers and prostitutes. He is working on his own and he's making newspaper headlines. It's time to put the brakes on Finch.
Meanwhile, Hugh Berry, the man who sorts out the paperwork to cover Lenny's illicit activities, asks him to take out a hit on his behalf.
A hit-and-run driver Trevor Bowyer rendered Hugh's grandson mentally disabled. But the driver only served two years for the crime. Lenny is left in no doubt that if he doesn't send his hit man to hug Bowyer, Hugh will find one of his own.
Lenny visits Finch in an attempt to bring him into line. But he finds a bitter, alienated and menacing man. Finch is everything Lenny feared he might become.
Leaving Finch's tower block, Lenny is furious to find Hugh Berry waiting outside, he's clearly tempted to hire Finch in order to take out Bowyer.
Lenny is targeting the kingpin of judicial corruption, Richard Blakeney, to expose his network of bent policemen and corrupt judges.
Blakeney is everything Lenny hates, and his network is everything he wants to bring down.
Lenny briefs Mercer on his delicate strategy. It involves exploiting Blakeney's hitman Georgie, who Calum and Mercer are spying on.
Mercer returns to the council flat to hear Calum talk about marrying his girlfriend Manuela. Marrying her would guarantee indefinite leave for the Colombian. As if to complete the dysfunctional family, Rose appears for dinner.
Mercer can't help but be secretly pleased she has come. At the end of the night, under the guise of returning her scarf, John goes to her house. He is in for a shock.
John arrives and sees her dressed up to go out and kissing Georgie in her doorway. Mercer retreats once more behind his emotional barricades.
Mercer confronts Lenny, demanding more information than they have been given.