The film begins in the celestial realms, with three superhuman entities--gods, or perhaps, angels--regarding the planet Earth - one of whom is played by a young, highly-made-up, shirtless George Sanders in an early role. Despairing of these "animals" that one of them continues to care about, two of them dare the third to conduct an experiment using these lesser creatures of that world to see if they can handle the kind of power over reality that might allow such beings to deserve to reach the stars. Choosing a human subject at random - though, necessarily, an ordinary if not downright foolish British subject - they bestow miraculous powers just short of their own upon one George Fotheringay, (Roland Young), an English middle-class haberdasher's assistant. Fotheringay enters the Long Dragon Pub and begins arguing with his friends about miracles and the impossibility of them. During this argument he calls upon his "will" to force a change and inadvertently causes a miracle: he makes an oil lamp turn upside down, without anyone touching it and with the flame burning steadily downwards rather than righting itself. He soon runs out of his miracle-sustaining willpower and is thrown out of the pub for spilling oil on the floor and causing a commotion.
When he arrives home, he performs the same trick with a small candle and finds that it works. He is so overjoyed that he spends the better part of the night working miracles such as lifting his table, lifting his bed, enlarging a candle-extinguisher to a brightly painted cone, making a kitten appear under it, and turning his bed into a cornucopia of fruits and fluffy bunnies. American cinematographer Harold Rosson, whom MGM frequently loaned out for British productions, has fun with what were still novelty special effects in 1936, using locked-down cameras to create chairs and tables that moved by themselves and appear and disappear at whim.
The next day, he makes his miracles known to the public - or rather that small portion of the clothing store where he works, impressing the girls with vanishing freckles and a co-worker with how quickly he can make shirts fold neatly and put themselves away. A policeman discovers these powers; when he begins to annoy Fotheringay, Fotheringay curses, telling him to "Go to blazes [hell]!" – where the poor bobby then finds himself surrounded by flames and swirling smoke. Fotheringay is horrified at his unintended action, and has the cop relocated to San Francisco where he finds himself in the midst of a traffic jam, and chased by American policemen himself.
Because Fotheringay cannot decide on how to use his newfound powers, he contacts Mr. Maydig, the local vicar. The vicar thinks up a plan to bring about a Golden Age and have Fotheringay abolish famine, plague, war and poverty—and, while they're at it, the British ruling class. They celebrate this by playing a miraculous trick on the local gentry, Colonel Wistanley (quite severely but endearingly overplayed by Ralph Richardson, who appears to be made-up for the stage, not film) having his whisky turn to undrinkable soap water, and his swords and weapon collection turn into a wild display of agricultural tools. When Whistanley hears about Fotheringay, he's baffled and then quite threatened by this vicar-inspired plan to change the world as he knows it, which he believes works just fine - Fotheringay points out that, of course, it works fine for the Colonel, but not really the rest of them, himself included. Exasperated at being unable to change the man's mind, the Colonel consults with his equally embattled fellow gentry and decides the only sensible solution is to shoot the man (his guns have helpfully not been converted by the earlier miracle). His first shot misses Fotheringay, who manages to make himself magically invulnerable.
Realizing that others wish to exploit him for their own ends - even the vicar - this incident inspires Fotheringay not to trigger a Golden Age after all, but instead to create an old-fashioned kingdom in which he is the centre of the universe. In a fit of reckless pompousness, Fotheringay changes the Colonel's house into a spectacular palace of real gold and marble. He then summons up all the pretty girls, not to mention the Colonel's entire regiment, dressed as Beefeaters, after which he summons the butlers in Essex, the leaders of the world, the teachers, musicians, priests, etc. He dresses up like a king and appoints the girl he loves as queen. He then commands the leaders of the world to create a utopia, free of greed, war, plague, famine, jealousy, and toil. Maydig begs Fotheringay to wait until the following day, so Fotheringay buys some time by making the Earth stop rotating. Alas, Fotheringay fails to consider the basic physics of the rotation of the planet and sends his palace, all living creatures and objects whirling off the world's surface. Civilization and all life (save Fotheringay) are obliterated as everything in the world flies through the air and is dashed to pieces.
The desperate and contrite Fotheringay calls on his powers one last time to put things back as they were before he ever entered the pub the day before, willing away his power to work miracles. Fotheringay appears again in the pub as in the early scenes of the film, again tries the trick with the lamp, and fails.Roland Young as George McWhirter Fotheringay
Ralph Richardson as Colonel Winstanley
Edward Chapman as Major Grigsby
Ernest Thesiger as Mr. Maydig
Joan Gardner as Ada Price
Sophie Stewart as Maggie Hooper
Robert Cochran as Bill Stoker
Lady Tree as Mr. Grigsby's Housekeeper
Laurence Hanray as Mr. Bamfylde, London & Essex Bank
George Zucco as Moody, Colonel Winstanley's Butler
Wallace Lupino as Police Constable Winch (billed as Wally Lupino)
Joan Hickson as Effie Brickman
Wally Patch as Police Superintendent Smithelle
Mark Daly as Toddy Beamish
Ivan Brandt as Player (a god)
George Sanders as Indifference (a god)
Torin Thatcher as Observer (a god)