Miss Cynthia Beeston [Margaret Rutherford]—a bold advocate of "Positive Thought"—finds her travel plans upended by a thick blanket of fog that blankets southern England. She insists on being moved from London Airport to Blackbushe Airport so she can try to catch a flight to Dublin, trusting that certainty and optimism will carry her through the delay. Her determination sets the stage for a farcical journey, even before the other travelers are fully aware of what fate has in store.
Harassed airline staff enlist an emergency relief coach, number 13, and recruit the inept Percy Lamb [Frankie Howerd] to drive the weary party. Percy is the kind of driver who seems to misplace town signs as easily as he loses his way, turning an already stressful assignment into a series of comic missteps and near-misses. Yet his blundering charm becomes a core part of the trip, the kind of hiccup that tests everyone’s patience while somehow keeping the mood buoyant.
Beeston is joined by a small caravan of travelers who bring their own quirks to the ride. Mild-mannered Henry Waterman [Toke Townley] clings to pulp-thriller fantasies, while Janie Grey [Belinda Lee] brings a sharper, more observing presence to the group. Ernest Schroeder [George Coulouris] adds a wary vigilance that will prove crucial when trouble looms. To satisfy a transport regulation, stewardess Nikki Nicholls [Petula Clark] is assigned to shepherd the group, adding a touch of professional calm to the otherwise improvised expedition. Rounding out the party is airline first officer Peter Jones [Terence Alexander], a steady presence who picks up the ride as an unplanned extra leg of the journey.
Unseen by the travelers, a brazen robbery unfolds at the airport: £200,000 worth of gold bullion is stolen from the bonded store and tucked away in the boot of the coach. The theft remains a hidden wind beneath the travelers’ casual excursion, a secret that will collide with their already fragile plans as the fog continues to swirl around them.
Two of the crooks are soon captured, and Inspector Henley [John Horsley] begins the slow work of piecing together what happened. Under interrogation, one crook breaks and reveals that the gold was stowed on the coach and that a mastermind known only as the "Banker" is orchestrating the heist. Henley radios Percy with the news, but the stubborn fog and the confusion of the road make locating the stash a difficult task. In a tense twist, Peter jolts the ride by pressing what seems to be a gun into Percy’s back and ordering him to keep driving, steering the group toward a deserted, booby-trapped village used by the Army for training.
The journey grows perilous as the coach enters a landscape of improvised danger. Schroeder’s discovery of a Sten gun raises the stakes, while Peter’s counter with a pistol complicates loyalties. Schroeder reveals that the gun Peter wields is not the only weapon in play, and a surprising dual identity emerges: Peter is working for airport security, whereas Schroeder is a police officer. The tension peaks as Miss Beeston is unmasked as the Banker, her gun now in hand, while her henchman Henry searches for a way to restart the coach.
Against this cascade of revelations, Percy proves pivotal. He had prior knowledge of the engine, having removed the rotor arm, a detail that becomes the crucial tool in the climax. With a swift boot of force and a sharp stone, Percy knocks the pistol from Miss Beeston’s grasp, turning the balance of danger back in favor of the group and averting a catastrophic spill of violence.
In the end, what began as a chaotic, fog-bound journey becomes a testament to chance, persistence, and the odd luck that binds a motley crew together. The uncertain road, the hidden gold, and the uneasy alliances all fold back into a narrative of resilience, humor, and a last-minute rescue that leaves the travelers to ponder what comes next after the fog lifts.
