The Lady Vanishes was Hitchcock's greatest critical and box-office success in pre-war Britain. It has endured as an audience favorite because it is so entertaining — artfully mixing comedy, mystery, romance, murder and suspense.
   Hitch used comedy as a prelude while introducing the key characters, then subtly shifted to suspense mode. The result is a thriller shaped by excellent writing, Hitchcock's signature directorial and camera technique, sterling performances and skillful editing.
   Filmed in early 1938 the film is notable as a comic satire on British blindness to Germany's growing threat in the run-up to WWII. While Hitchcock's social commentary did not obscure the film's entertainment value, it did express his impatience with appeasement sentiments within the UK, and Britain's insularity in general, comedically conveyed by a pair of stiff-upper-lip cricket fans contemptuous of all things un-British.
   Indeed, when the "lady vanishes" a cover-up is conducted on the train by a gang of mysterious Germans, Italians and Czechs – while most of the English passengers remain clueless.

    In Alfred Hitchcock's most quick-witted and devilish comic thriller, the beautiful Iris (Margaret Lockwood), traveling across Europe by train, meets a charming spinster (Dame May Whitty), who then seems to disappear into thin air. The younger woman turns investigator and finds herself drawn into a complex web of mystery and high adventure. Also starring Michael Redgrave, in his debut film performance, as Gilbert, The Lady Vanishes remains one of the great filmmaker's purest delights.

   The Lady Vanishes has been immortalized in film literature – hundreds of critics and film historians have written thousands of articles – and The Guardian's Philip French says it as well as anyone, excerpted below:

   "Hitchcock and railways go together like a locomotive and tender. He loved them, they figure significantly in his work and never more so than in The Lady Vanishes. Much of what happens could only take place on a railway line – passengers delayed together by an avalanche; classes compartmentalized; strangers trapped together as they're transported across a continent; an engine driver killed in crossfire; a carriage disconnected and shunted on to a branch line; an intrepid hero struggling from one carriage to another outside a fast-moving train as other locomotives rush by; clues in the form of a name traced in the steam on a window, and the label on a tea packet briefly adhering to another window; [and don't forget the nun in high heels!] and above all the enforced intimacy on this rhythmically seductive transport moving on its own tracks, independent of the changing landscape around it.

   "The screenwriters, Frank Launder and Sidney Gilliat, both much influenced by Hitchcock, had radically reworked the plot and the characters and most significantly had invented the insouciant cricket-loving Englishmen, Charters and Caldicott. As played by Basil Radford and Naunton Wayne, they were to become the greatest comic duo ever created in the British cinema, national archetypes that stamped themselves on several generations of moviegoers.

   "The casting, in which Hitchcock was closely involved, was perfection, most crucially that of Margaret Lockwood and Michael Redgrave as Iris and Gilbert, the attractive romantic couple at the centre, who meet cute, bicker beautifully and share a delightfully British sense of humour. Both became stars in this picture and proved themselves the equals of such sophisticated 30s Hollywood couples as Powell and Loy, Grant and Hepburn, Lombard and Gable.

   "Although The Lady Vanishes comes up fresh whenever one sees it, it's a film that derives its depth and urgency from the troubled times in which it was made. It was shot during the spring and summer of 1938 in the months leading up to Neville Chamberlain's capitulation at Munich, and Iris and Gilbert are passengers on a ship of fools, a compartment of British clowns adrift in a hostile Europe, surrounded by inimical foreigners in a world on the brink of war."