Somewhere in London a refined gent in a bowler hat walks along the road with flowers and chocolates seemingly on his way to a date. He stops at a jeweller's window and looks at the rings. Suddenly he throws the box through the window, and unexpectedly grabs the jewels. A Citroen DS rushes up and he gets inside to join his friends. The police give chase and they are doing well until stopped at a junction for a fire engine to pass. They are caught and sent to Wormwood Scrubs. Following release, the three incompetent criminals go to a fire engine salesroom where the salesman extols the virtues of each. But they cannot afford £5000 for a new engine. They go to a scrap yard and buy an old engine. They have decided that a fire engine is the least likely form of transport that the Police would be delayed by traffic. They steal a well-maintained working 1930s fire engine, stored in a remote fire station, and swap it for their scrap engine of the same type. They then burn down the fire station to hide the theft, leaving the burnt out scrapper in the debris. They store the engine in a big shed in Smithfield. They find a suitable jeweller on a corner near Berkeley Square. They get uniforms in a costume shop. Testing their theory, their first attempt to rob a jewellers shop ends in disaster. While Harry is dodging the police, as he wanders around the target jeweller, he escapes into a show of wedding dresses. Here he meets the French owner Chantal and pretends he is the son of Lady Hamilton, one of her rich clients. He gets a dinner date with her. Meanwhile, Bernard and Alfie in the fire engine are flagged down by a desperate home-owner whose basement flat is flooding and mistakes them for the real fire brigade. Their attempts to pump out the flat make matters worse, as they only add water, and they flee the scene with hoses trailing behind them as the real fire engine arrives. Failure only makes them more determined, but they must be more professional and must pass as trained firemen; their obvious incompetence at the flooded flat nearly ruined their plans. Acquaintance "Arson Eddie" is unwilling to help them, as he is devoted to creation of the ‘sacred flame’. He knows all there is to know about starting fires, but next to nothing about putting them out. A chance conversation heard outside a fire station puts them onto Withers, a fire chief dismissed from the service for arson, theft and conduct unbecoming. He is persuaded to train them all in exchange for a share in the proceeds of the bank job. Chantal's salon is next to a bank and they decide a fire in her basement would be a suitable ruse to have them conveniently close to the bank. They return to Arson Eddie for a fire-raising scheme. Chantal has a meeting with her boss Madame Colette who reveals they are in financial difficulty but the dress collection is insured for £20,000. "Blimey" she says revealing her true cockney accent before returning to her French pretences. Arson Eddie arrives pretending to be a potential client, Mr Mountbatten. He is enchanted by the women but fails to start a fire. However, Madame sets fire to the curtains as part of her own plan. The building is soon ablaze. The robbery takes place from the basement but the fire above is very real. Meanwhile the real fire brigade arrive. All goes to plan and the thieves escape with a fire hose stuffed with banknotes. Collette and Chantal spot Harry and "Mr Mountbatten" in their firemen uniforms and exclaim their surprise. A policeman overhears and gives chase. It is only as they make their getaway that they are flagged down by two young girls whose treehouse is on fire, and once more they are required to join in the fighting of a real fire... undeterred, well equipped, and above all trained, they join in. It is a pity that Alfie attaches the wrong hose to the pump and covers the scene of the fire with the stolen money instead of water. The film draws to a close with the crooks sitting in the ‘Black Maria’ on the way to their next stay in prison; in the window behind the van a Royal limousine is visible in the distance. Seeing it, Bernard remarks he has just had another idea for the perfect getaway vehicle...
