It is the end of the world, with only one man standing as the sun goes out in a blood-red flash. A solitary raven caws as the oceans engulf the earth. Civilisations topple into a blazing canyon, lightning screams across the heavens and rocks burst like popcorn in the global meltdown. Darkness dawns. Nobody did the apocalypse as well - or as frequently - as John Martin.
Martin (1789-1854) was born in Northumberland, in the northeast of England, and was a phenomenon in his own right. He had no formal training, yet no other artist of the 19th century had a greater public reach than he, and not just in Britain but across the English-speaking world. By the time his three-part Last Judgment reached St George's Hall, Bradford on its English tour, just after his death, the paintings had already been "inspected by upwards of two million persons". Many more would see them abroad.
The vital statistics are advertised in the handbill: sixpence to see three masterpieces, "each picture 13ft by 10, and valued at 8000 guineas - the most sublime and extraordinary pictures in the world!". The audiences were ushered in, held back from the candlelit images by cordon.
The show made a mint. This was art as entertainment; painting as sensational performance.
And so it still is, from first to last, at Tate Britain. Martin's work runs a fine line between drama and melodrama, each painting delivering its fresh horror with spectacular force.
The show opens with a raving old whitebeard about to fling himself from a crag miles above a seething torrent - don't do it! - and never lets up from one cliffhanger to the next. It is both awesome and riotously awful.
Imagining the worst: that was Martin's speciality. The Tower of Babel collapses. Sodom and Gomorrah are obliterated. Etna erupts - look behind you! - and Pompeii is engulfed. Babylon falls, and Nineveh, and Jericho, and pandemonium is naturally unleashed. The contents of the Book of Revelations are fully illustrated, along with Exodus and Paradise Lost - thrilling, edifying and over the top in roughly equal measure.
Martin found form quite early in his career, which began as a painter of inn signs, glass and crockery (the surviving dinner plate is in this show).
For all the compositional variations, the essentials do not alter greatly: dizzying height and depth, colossal skies dwarfing whichever culture is seconds from destruction, an unimaginably cavernous space opening in the back of each image. Huge armies are pitted against tiny solo figures.
Plunging gorges have their circling eagles, approaching infernos are reflected in polished objects in the foreground, the skylines of ancient cities recede in rectilinear perspective, mocked by the swirly doom-clouds above.
Every comparison you can think of is obvious and true. Martin's paintings anticipate biblical epics and disaster movies and CinemaScope; sci-fi illustrations, concept albums and heavy-metal graphics; Spider-Man (look at the boneless figure of Sadak somehow slithering up a rock as big as a skyscraper) and the avatars of video games. Film directors have acknowledged the immense debt, from D.W. Griffith to Cecil B. DeMille and Roland Emmerich.
So that is a tremendous aspect of Martin's work: its sheer inventiveness, its box of tricks, its innovative special effects. Though he has debts of his own as well. There are lifts from Blake, Fuseli, Turner and even Constable in the flickering proto-impressionist impasto of his late paintings with their glistening, encrusted surfaces; and all were at some time competing for wall space at the Royal Academy.
The Tate Britain show gives a strong sense of the contemporary art market: the fortunes made by dealers who bought and then toured Martin's pictures; the need to make paintings large enough to be noticed high on the Royal Academy walls, but not so large that a collector could not house them; the money he was forced to make from prints when he couldn't sell his paintings.
These little prints are more amazing than the grand machines - Satan holding court in what looks like a solo performance in the Albert Hall (decades in advance); imaginary cities stretching away into the misty air that look remarkably like mezzotints, or even sepia photographs, but turn out to be tiny watercolours.
You see Martin dreaming up, on a delicate scale, all sorts of things he had never seen: Asian peaks, Egyptians, ziggurats, the stones of Avebury when it was first built, exotic trees, volcanic eruptions, even dinosaurs (is he the first dinosaur artist?) - and in each case the quick intimacy matches the potent vision.
And imagination is everything in Martin's art. Faced with an actual landscape or episode (the coronation of Queen Victoria, say) his paintings are hopelessly banal. Equally, the bigger the canvas, the harder each picture has to work for its living and imagination is sacrificed to the demands of showmanship.
Martin does people like gesticulating dolls, hands flung up in ecstasy - thank God! - or horror - oh no! His waterfalls are like cartoon spills drawn in correction fluid. His lightning is worked out with a ruler and set square. The pictures are so densely detailed, viewers needed a printed guide (facsimiles are available in this show).
It is not an art you can believe in, no matter that it might make you gawp and shudder just to think of such outlandish catastrophes. But it is an art that benefits from very particular viewing conditions, and it's to the credit of Tate Britain that these have been mimicked here.
The three-panel Last Judgment is performed as a son et lumiere. Each panel gradually starts to glow in small vignettes - God, Satan, the saved, the damned - as something approximate to candlelight passes across it.
Then the pictures (or rather the high-resolution reproductions projected upon them) begin to shimmer, warp and quake. A voiceover warns of your own impending death.
Lurid as this may sound, it is only a more sophisticated update of the 19th-century technology. The paintings "come to life" as they must have done for electrified viewers in Bradford. You see what they saw, momentarily, before the houselights go up and these paintings - so hard to look at for long - are once more inert. Observer
* John Martin: Apocalypse is at Tate Britain, London, until January 15By Laura Cumming