On October 12 1954, Alfred Hitchcock was shooting on location in Morrisville, Vermont, when the overhead bracket supporting a VistaVision camera snapped. Weighing 850lb – the same as a car – the camera unit dropped through the air, swiped the director's shoulder and rolled over, pinning a crew member briefly to the ground. It was the nearest the master himself came to violent death: just a few inches to the side and it would have smashed that unmistakable domed head like a peach and provided cinema theorists with any number of irresistible, macabre metaphors. Hitchcock calmly ordered filming to continue with a replacement camera. Later he packed up, however, declaring himself unsatisfied with the weather in Vermont, and moved the shoot back into the studio in Los Angeles.
The film was The Trouble With Harry. Perhaps the near-miss was a bad omen, because Hitchcock's most experimental, subversive and uncompromisingly strange black comedy – about people in a small town who can't decide what to do with a dead body – was a catastrophic commercial failure. It lost half a million dollars at the box office and was unavailable for decades after release. The colossal Hitchcock retrospective just getting under way at London's BFI Southbank has already elicited many elegant articles, endlessly rehearsing the accepted canon: Psycho, Vertigo, North By Northwest, The Lady Vanishes, The Birds … and so on – but The Trouble With Harry doesn't make the cut.
This exclusion feels more pronounced in the context of discussion of Hitchcock as a surrealist. Surrealist moments or elements such as the Dali-designed dream-sequence in Spellbound get a lot of attention, understandably; but The Trouble With Harry gets passed over. Hitchcock's most completely surreal achievement happened behind his cheerleaders' backs: a film whose eerie dream procedure is pursued from the opening titles to the final credits. Hitchcock wryly called his box-office flop an "expensive self-indulgence"; to Truffaut, he said that "the humour is quite rich". Audiences came along to it the way Broadway theatregoers might sit down to something by Agatha Christie or Ira Levin. Instead, Hitchcock gave them his Waiting for Godot. Now the moment has come to reclaim The Trouble With Harry as radical absurdist cinema.
It was adapted from a novella by British author Jack Trevor Story, by one of Hitchcock's favoured screenwriters, John Michael Hayes (Rear Window, To Catch a Thief, The Man Who Knew Too Much). The action was transplanted from its original English countryside setting to a folksy, gently autumnal Vermont. It begins with a scene of intense, captivating strangeness. A little boy runs through woodland with a toy gun and, in a world of his own, pretends to fire it. He then freezes rigid, terrified, on hearing real gunfire. It is the only time in the movie that anyone looks scared. Are real grownups firing back at him? Has he somehow magicked them into being? All the while Bernard Herrmann's unsettling score offers premonitions of his Psycho. The boy hears shouts in the undergrowth, and then finds a man's dead body with blood trickling from what looks like a bullet hole in the head.
But wait. The body isn't sprawled on the ground, arms and legs flung wide, the way it surely would be in an undisturbed crime scene. It is stretched out, neat and proper, as though laid in an invisible coffin, with polished shoes and a slightly dandyish suit and tie. Twice, Hitchcock gives us the foreshortened camera angle with the kid looking down the length of the corpse, and it looks as if the great big feet are protruding from his little frame.
Subsequent events show that a number of people have a reason to feel uneasy (the word "guilty" isn't quite right) about the deceased, whose name turns out to be Harry Worp. There is Jennifer, played by Shirley Maclaine in her first movie role, a pretty young widow, mother of the little boy. There is the roguish retired sea captain, Wiles (Edmund Gwenn); Mildred Natwick, a John Ford regular, plays the simpering spinster Miss Gravely with whom Captain Wiles is enamoured. John Forsythe (who as a silver-haired older man would later find fame as Blake Carrington in 80s TV soap Dynasty) gives a laconic, Bogartian performance as a handsome artist called Sam Marlow who falls in love with Jennifer.
Each of them prods the corpse, or frowns at it, or sighs over it, or worries that it will cause trouble – or, in Jennifer's case, laughs with unfeigned relief and delight at the sight of it. (That nice Shirley Maclaine!) But nobody goes into shock and astonishment and immediately calls the cops, the way they would in real life, or in a conventional movie. A conventional movie would introduce a police inspector, who would interrogate all these people, and their connections with the deceased would be made apparent to the audience that way.
Not here. Eerily, weirdly, each character is basically unconcerned about that most horrible of things, a dead body. They discuss having tea over the body. They discuss their love lives over the body. (Very recent attempts at assault and rape are remembered with a detached smile.) Jennifer giggles heartlessly; Sam draws the cadaver. Are they all monsters, or suffering from mass psychosis? No. Hitchcock's genius is to keep strictly to the bad-dream logic. These are all nice people in a silly spot of bother, behaving as if they are in Vincente Minnelli's Meet Me in St. Louis. They walk and talk and move around the screen like lucid somnambulists.
What Hitchcock did in The Trouble With Harry was to remove the suspense: an extraordinary act of formal daring. (His Rope, made in 1948, centred around a dead body, too, but here there was a far greater sense of suspense: the two students are desperate that the body concealed in their flat remains a secret.) In Harry, even the arrival of the deputy sheriff and the doctor in the final scene is not suspenseful or climactic: more a woozy, bizarre comedy starring people who look like human beings but aren't. They should be astonished at the body in the bath; they are perplexed but calm.
The nearest comparison is probably with Eugene Ionesco's play Amédée or How to Get Rid of It (written in 1954, the same year) about a playwright and switchboard operator who have to deal with a dead body in their apartment that is continually growing. In the cinema, the nearest in spirit could be Luis Bunuel's 1072 film The Discreet Charm of the Bourgeoisie – but even there, the strangeness is partly explained by dreams. In Harry, everyone is wide awake.
Is Hitchcock, in fact, tipping us a sly wink with Sam, the misunderstood artist whose modern experimental canvases are sold by the local postmistress? She hangs one the wrong way up. With an indulgent chuckle, Sam turns it the right way round – but isn't the least bit cross. At the time, no one knew which way up to hang The Trouble With Harry. It's time to take another look.
• The Genius of Hitchcock is at the BFI Southbank, London SE1 until 30 November. The Trouble With Harry will screen on 20, 25 and 28 September.