'Spiv' Bar Gorman walks through Soho's market streets, recognised by all. He is the business manager for 'Knucksie' Sugiani, an Italian 'warlord' racketeer involved in numerous criminal activities over a 10-year period, including murder, counterfeit notes, smuggling, trading in stolen goods and ration coupons.

Annie Foss, a French ex-girlfriend of Sugiani, hears that the dead body of her friend Milly Sharp has been recovered from the River Thames. When interviewed by Inspector Rendall of the Yard, she tells him that gang member 'the barber' strangled Milly on the orders of Sugiani. Rendall asks her to identify Milly's body. In a nearby café, Linda Medbury, an American reporter working for the Evening Echo, sees Annie in a state of shock, and befriends her. Linda tells her editor of the story and asks to cover it, even though she is a fashion specialist. The Echo prints the story, which annoys Sugiani.

Gorman arrives at Linda's flat, forces his way in and warns her to stay off. Sugiani, waiting outside, enters, and she threatens more stories about his racketeering. Linda orders them both to leave, but not before Gorman realises Annie is hiding in the bedroom, and she leaves with him. Linda manages to track down a frightened Annie (who is unwell with a weak heart) and wants her story.

Linda is engaged to marry ex-WW2 commando captain 'Jumbo' Hoyle, a fellow Echo journalist. While planning their honeymoon, he reminds her what happened to previous journalists who took on Sugiani. Hoyle visits Pudd'n Bason's gymnasium, which is frequented by porters from Billingsgate, Covent Garden and the like, and asks Bason's lads to provide protection for Linda, and launch an 'illegal' raid on Sugiani's rackets. Hoyle plans his 'Operation Noose' like a military operation, emphasising the need to act within hours, before Sugiani can bring in reinforcements. A printing press run by forger 'Slush' is raided by Hoyle's gang, and 'Greasy' Anderson, a diamond smuggler working for Sugiani, is arrested and talks to Rendall. Sugiani hears of these raids, and tries (without success) to bribe Rendall.

Rendall visits the gym and warns Pudd'n and his gang not to act outside the law, but let the police handle the racketeer. Maffy, who makes tea at the Gym, is later killed by Sugiani's men, which only strengthens Pudd'n's resolve to take them on.

A desolate Annie, seeing that Sugiani has another girl, visits the 'Blue Moon' nightclub, and is captured by the sadistic 'barber'. Later she is found dead from a heart attack, following evidence of burns. Both Rendall and Sugiani are at Annie's flat beside her coffin when Linda visits and accuses Sugiani of being responsible.

At the club with his new girlfriend, film star Mercia Lane, Sugiani learns that his petrol dump, market and warehouse have all been raided by Hoyle's gang.

After Linda and Hoyle threaten to name Sugiani as 'London's Number 1 racketeer', Sugiani pays 'the barber' to 'remove' Linda, but Hoyle's boys prevent him and she manages to flee. Hoyle finds Linda's flat empty. Linda visits Gorman, and refuses to leave the office until she is able to confront Sugiani directly. Rendall's officers have the Blue Moon club surrounded. Gorman, hearing of this, flees with Nelly, the dressmaker, while Linda and Mercia struggle with Sugiani. Hoyle's gang enter the club at the end of a dance act, followed by police. Stripping to their football shirts, they start a brawl, during which Hoyle rescues Linda, Mercia loses her dress and Sugiani is chased on to the roof. By means of a fire escape, Sugiani enters the Catholic church opposite. Rendall is tipped off, and he and his men enter and find a man in the pews seemingly in deep prayer, but he falls forward. It is Sugiani with a noose round his neck. His killer, 'the barber', flees from the church and is run over by a passing car.

The police enter dressmaker Nelly's store and arrest Gorman. Mercia, still in her undies, cooly exits through the front door and hails a taxi, soon followed by Linda and a limping Hoyle, who walk away arm in arm.