As southern England lies fog-bound and all flights from Heathrow are grounded, a handful of passengers manage to leave the airport by coach bound for Blackbushe Airport and a chance of getting a flight to Dublin. All is not what it seems with them, however, as the bus holds £200,000 in stolen bullion, and someone on board is the villain!
Frankie Howerd, in his first big-screen role, plays Percy, the unwitting, unassuming driver, and as such provides most of the comedy moments as he tries to unpick the plot. Apparently cautious about breaking into film, he only agreed to do it so he could work with Margaret Rutherford, whom he had long admired.
Rutherford plays a bossy academic and 'positive thinker' with her usual aplomb - a role that ironically mirrors the role Howerd was to take on fourteen years later in Carry On Doctor. A very young Petula Clark also shines as the stewardess assigned to look after the passengers. Also aboard are businessman Ernest Schroeder, whom Percy suspects is the villain, mild-mannered Henry Waterman, pulp-fiction addict Janie Grey (Belinda Lee) and airline pilot Peter Jones (Terence Alexander).
There’s a lovely quaintness about this movie, right from its early views of a very pre-commercialised Heathrow Airport, to the mixture of passengers and their quirks and foibles, such as Janie's inability to see the tense plot unwrapping before her very eyes, because she's still wrapped in a paperback thriller.
But who is the villain? And what - if anything - can be done about it?