After leaving the army and university, Stanley Windrush is determined to make his way in the world and decides on a career in industry. After a number of unsuccessful interviews, he is contacted by his uncle, Bertram Tracepurcel, and his old army comrade, Sidney De Vere Cox.

Tracepurcel is director of Missiles Ltd, an engineering firm which is about to sign a large arms contract with an Arab government. He and Cox suggest that Stanley should gain experience as part of the factory's workforce, but advise him not to reveal his family connections.

Stanley's enthusiasm immediately convinces his work-shy colleagues that he is a time-and-motion observer secretly planted by the management. They report their suspicions to shop steward Fred Kite, who confronts Stanley and discovers that he is not a union member. Kite leads a delegation of the works committee to see Major Hitchcock, the company's personnel officer.

Hitchcock is relieved that the workers have not detected a genuine time-and-motion expert named Waters, who is about to start work. He offers to sack Stanley, whereupon the works committee allege victimisation and insist that he is kept on. Stanley takes lodgings with the Kite family.

Tracepurcel and Cox meet with the Arab government agent, Mr Mohammed. They tell him that Missiles Ltd can no longer fulfil the contract due to the industrial unrest which Stanley is bound to provoke. The order can be passed over to Cox's company, Union Jack Foundries Ltd, in which Tracepurcel secretly has shares. The increased cost to Mohammed's government will then be split between the three of them.

Waters talks to the unsuspecting Stanley, who demonstrates that the factory's accepted work rate is well below its potential. He reports back to Tracepurcel and new work schedules are introduced. Kite calls a strike and Stanley is sent to Coventry. To keep the strike going while Mohammed makes the necessary arrangements with his government, Cox calls in the media, and soon Stanley has become a national hero.

Stanley's authoritarian Aunt Dolly visits the Kite household and convinces him that he must return to work. He crosses the picket line, revealing in the process that he is Tracepurcel's nephew. Furious, Kite throws him out of his house, to the distress of his daughter Cynthia, who is in love with Stanley. Mrs Kite announces that she too is on strike, and she and Cynthia leave to go and stay with her sister.

The arms contract is reallocated to Union Jack Foundries Ltd, but the workers there have come out in sympathy with Missiles. Soon the strike has spread nationally, creating an industrial crisis. His plan having backfired, Tracepurcel sends Hitchcock to talk to Kite and agree terms for dismissing Stanley. They decide that an allegation of ill-health brought on by overwork is the best way to get rid of Stanley, and to demonstrate the unfeasibility of the new work schedules at the same time.

Stanley, Tracepurcel, Kite and Mohammed all agree to take part in a live television programme to debate the strike. Prior to transmission, Cox reveals to Stanley that he has been duped, and offers him a bag full of money if he will resign and keep quiet. During the broadcast, Stanley denounces the greed and self-interest of everyone involved in the dispute, and throws the money around the studio.

An undignified scramble follows, and Stanley finds himself charged with causing an affray. Tracepurcel and Kite collude in ascribing his outburst to ill-health due to overwork. Bound over to keep the peace for a year, Stanley retires to the sanctuary of the naturist camp where his father is already a resident.