An indolent aristocrat gets more than he bargained for when he hires a competent but silently devious manservant.

Trouble is brewing in the banana republic of Bianco for both His Excellency, El Presidente, and the British Consul, Brant. Rebels, led by Diego De Costa, the trusted "Minister of the Marines and the Customs" and Lieutenant Enricquo, the gunnery officer of the small republic's one battleship, have taken over the battleship, and the town. Most of the British citizens have taken refuge at the Consulate or have been evacuated to the small cruiser in Bianco's port, the "H. M. S. Audacious." But there are two major issues; the Consul's daughter, Pamela, and Canadian Lieutenant Bill Armstrong have been kidnapped by the rebels and now held hostage on the battleship "El Mirante," and El Presidente was visiting the consulate when the war broke out and is now under the protective custody of the British Empire.

A private eye is hired to go undercover at a health farm, but before he can find out why his client is murdered.

The film hinges on the love triangle between a young aristocratic lady on the run (Cleonie, played by Hazel Terry), the murderous Varennes, Citizen-Deputy of the Revolution who saves her by disguising her as his nephew (Nils Asther) and finally the Marquis of Corbal of the film's title, played by Hugh Sinclair.

A study of heredity in man, showing how both good and bad characteristics are passed on from one generation to the next.

Two business partners are having woman trouble. One wants to marry his secretary and the other is set to marry a wealthy aristocrat. When the partner who wants to marry his secretary lets her go before he proposes to her, the woman confused woman tries to commit suicide by jumping into a river. Complications ensue.

This long-lost British comedy features a wealthy heiress rescued from the clutches of a scheming foreigner by a pair of bumbling market traders. But the plot plays second fiddle to the comedic performances of stalwarts Wally Patch (one of Britain’s most prolific character actors) and the much-loved Margaret Rutherford. Patch and Vedey make a dynamic double-act whose clowning keeps the film zipping along, while Rutherford’s imperious proclamations on etiquette are priceless. Irene Handl adds some ooh-la-la to the role of a French maid, and director Carstairs ably keeps them all under control.