In 1936, Jack Comer is imprisoned for violent anti-fascist actions in London. Out six months later, he takes work as muscle for illegal club owner and racetrack racketeer Darky Mulley, and is now regarded as a threat to London’s dominant gang, co-ruled by Alfred White and Charles Sabini.

When WWII breaks out, Sabini and his Italian crew are rounded up as state enemies. Jack is conscripted, but is declared mentally unfit after attacking his drill instructor. When Alfred White dies of a heart attack, his incompetent son Harry declares war on Jack. In the then biggest raid in British history, Jack steals ration coupons from the Romford Food Office, securing his reputation as King of London’s underworld.

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The World War over, robber Billy Hill, fresh out of Wandsworth prison, asks if his crew can work for Jack’s expanding organisation. After Harry beats up Billy, the latter, helped by sadistic henchman Frankie Fraser, locates Harry’s hangout and slashes him. Billy’s wife Aggie learns that he has taken up with prostitute Gypsy, and asks if she can run a club herself. At that club, Jack falls for Rita, and marries her, even as his own fortunes decline. Meanwhile Billy, aided by journalist Duncan Webb and a daring Mailbag Robbery, builds a reputation.

After various increasingly violent fallings-out between Jack and Billy, Jack retires with the pregnant Rita in 1956. Up and coming twins Ronnie and Reggie Kray ask Billy, now King, for work.