[4] The film is set in the North West Frontier Province of British India (now within modern Pakistan).

It explores the ethnic tensions within British India after Muslim rebels attack a fortress and kill a Hindu maharajah.

On arrival at Haserabad, Captain Scott sees that many local Hindus and Europeans are leaving on the last train to Kalapur.

In the railyard, the British captain discovers the "Empress of India", an old railway engine cared for by its driver Gupta, affectionately known as Victoria.

They include Mrs. Wyatt, Prince Kishan, arms dealer Mr. Peters, British expatriate Mr. Bridie, Lady Windham (the governor's wife), two British Indian Army NCOs, and Dutch journalist Mr. Peter van Leyden (Herbert Lom).

Victoria quietly freewheels down a gradient and out of the yard, but when her whistle is accidentally sounded, Gupta fires the engine and crashes her through the outer gate.

Despite being told not to by Captain Scott, Mrs. Wyatt leaves the carriage and finds one survivor, a baby concealed by his mother's body.

Mrs. Wyatt spots the signaling flashes of a heliograph on a mountain summit, and everyone quickly realises that the Muslim rebels are sitting in ambush in the surrounding hills.

Scott returns to the carriage with the young prince after spotting more rebel heliograph signals, but they are saved when the machine gun is knocked off balance by a kick from Mr. Bridie.

The Muslim rebels chase the train on horseback but are thwarted when Victoria enters a two-mile-long hillside tunnel.

At the station, young Prince Kishan is met by his Hindu entourage, while Gupta is taken to hospital, and Lady Windham is informed that her husband, the governor, is safe.

On learning Prince Kishan may yet fight the British, as his father instructed him, Scott quotes Kipling ("Be thankful you're livin', and trust to your luck, And march to your front like a soldier") before he and Mrs. Wyatt leave together carrying the infant she had saved earlier.

Although it now stands within Man Sagar Lake, the water levels in the 1950s were so low, horseriders could be filmed riding up to its entrance.

"[21] George MacDonald Fraser praised the performance of I. S. Johar: It was a true rendering of a type imitated successfully by Peter Sellers and others, the quaintly-spoken 'Oh-jollee-good-Sahib' funny Indian – a genuine character familiar to everyone who knows the subcontinent.

[22]Fraser admired the film and More's performance saying "he had a cheery truculence that was much closer to the real Imperial type than the conventional stiff upper lip."

"[23] Filmink called it "a rousing adventure set in India with excellent action/spectacle mixed in with sooky Imperial propaganda, and Lauren Bacall ranks with Sally Ann Howes and Kay Kendall as More’s most effective love interest.

After original director Alexander Mackendrick was fired, star Gregory Peck saw Northwest Frontier and agreed for Thompson to take over.