A manhole opens at night in an empty street and out climbs Lieutenant-Colonel Norman Hyde (Jack Hawkins) in a dinner suit. He gets into a Rolls-Royce and drives home. There, he prepares seven envelopes, each containing an American crime paperback called "The Golden Fleece", half a £5 note and an unsigned invitation from "Co-operative Removals Limited" to lunch at the Café Royal. He then posts the envelopes to seven former army officers, each in desperate or humiliating circumstances.A few days later, the men in question turn up at the Café Royal. After lunch, Hyde dismisses the waiters and introduces himself. He hands out the second halves of the £5 notes and asks their opinion of the novel in which a robbery is committed by experts. When they show little enthusiasm, he expresses surprise given their backgrounds and asks: "You're all crooks, aren't you? Of one kind or another". Touring the table, pouring out the brandy, he reveals why they were obliged to leave the British Army and their unenviable present occupations:Major Peter Race (Nigel Patrick) was a transport officer who resigned before his black market ring was uncovered in post-war Hamburg. He earns a poor living in unlicensed gambling and lives at the YMCA. He prides himself on his high breeding and addresses men as "old darling";Major Rupert Rutland-Smith (Terence Alexander) is the hen-pecked husband of a wealthy young woman who delights in pulling his strings because he depends on her money. She also has affairs to which he can only turn a blind eye;Captain Mycroft (Roger Livesey) was a quartermaster dismissed for public gross indecency. He is now a con-man impersonating vicars and priests. He also enjoys lewd books;Captain Martin Porthill (Bryan Forbes) was dishonourably discharged for killing suspected members of the Cyprus-based EOKA terrorist organisation (Cyprus was a British colony at the time). He now works as a piano player in nightclubs and as a gigolo to middle-aged women;Captain Stevens (Kieron Moore) was fascist follower of Oswald Mosley before joining up when World War Two began. He now runs a gymnasium. A homosexual, he needs money to pay a blackmailer (male relationships of a sexual nature being illegal at the time);Captain Frank Weaver (Norman Bird) was the head of a bomb disposal squad who tried to defuse a bomb while drunk, killing four of his soldiers. He has been a teetotaller ever since and owns a small shop fixing clocks and watches, living with his garrulous wife (Doris Hare) and ageing father-in-law;Lieutenant Edward Lexy (Richard Attenborough) is a communications specialist who was dismissed for selling information to the Russians. He runs a struggling repair shop for radios and fruit machines.Hyde tells them he has no criminal record himself but does have a grievance for being made redundant by the army after a lengthy career. He is now aims to rob a bank using the team's skills!Race follows Hyde home. He is interested in the scheme but warns Hyde to watch out for the others, who might just double-cross him. Hyde agrees, yet insists each man receive an equal share of the loot because "the one, sure way to disaster is for someone to get greedy". After talking the plan over, Race agrees to Hyde's terms, stating that "you're losing a friend, but gaining a second-in-command", to which Hyde answers, "I'll settle for that".The gang meet under the guise of an amateur dramatic society rehearsing "Journeys End" to discuss the plan (during which they are interrupted by a rather camp Oliver Reed). They then move into Hyde's house and begin to live a strict military regime of duties, varying from cooking to preparing for the robbery. Hyde knows that a million pounds in used notes is regularly delivered to a City of London bank and has details of the delivery. What they need now is the equipment to pull it off.They raid an army training camp in Dorset for arms and supplies. Hyde, Mycroft, Porthill and Race distract the soldiers by posing as senior officers on an unscheduled food inspection. The others steal weapons while posing as telephone repairmen, speaking in Irish accents to divert suspicion to the IRA (Irish Republican Army) terrorist organisation.Equipment, including smoke bombs, are prepared in a rented warehouse. Race steals various vehicles including a truck and false number plates are also made. At one stage they are disturbed by the chance passing of a policeman who offers to keep an eye on their premises as part of his beat.In Hyde's basement, the gang train for and plan the robbery using maps and models. On the eve of the operation, Hyde destroys the plans and sighs: they have reminded him of his days of military glory.The robbery is bloodless and precise. Using smoke bombs, sub-machine guns and radio-jamming equipment, the gang raids the bank, near St Paul's. The loot is seized without serious injury and the robbers successfully escape, every stage having been carefully planned and practiced.At Hyde's house, celebrations are interrupted by the unexpected arrival of Hyde's old friend, Brigadier "Bunny" Warren (Robert Coote), who drunkenly recalls the old days. One by one the members leave carrying money-filled suitcases. Then the telephone rings: Hyde is told that police and soldiers surround the house.Leading the police is Superintendent Wheatlock (Ronald Leigh-Hunt) from whom Hyde learns the fatal flaw in his plan: a small boy outside the bank had been noting car registration (licence plate) numbers in his note book, a common hobby at the time. The police, discovering the number, found it had been noted by the policeman who visited the warehouse, who had also noted the number of Hyde's own car. Thus a link was formed between the robbery and Hyde.Hyde is escorted to a prison wagon in which he finds the rest of the League of Gentlemen "all present and correct".