Three prisoners nearing the end of their sentences — Dodger Lane, [Peter Sellers], Jelly Knight, [David Lodge], and Lennie the Dip, [Bernard Cribbins] — find their lives tugged toward a startling proposal when a slick vicar arrives seeking to help them readjust to life on the outside. In reality, the conman Soapy Stevens, [Wilfrid Hyde-White], pitches a daring plan: break out, rob a valuable diamond stash, and then return to the prison to preserve flawless alibis. The trio are encouraged by the prospect of a clean getaway, and they dash from the cell block into a carefully crafted escape route.
With the help of Dodger’s girlfriend, Liz Fraser as Ethel, and Lennie’s mother, Irene Handl as Miss Price, they slip out in a fake prison van orchestrated by Soapy Stevens, turning a routine day into a high-stakes caper. The plan hinges on timing and misdirection, and for a while the pieces click into place as they maneuver past wary guards and a system that trusts nothing and questions everything.
Yet trouble arrives in the form of a new chief authority, a disciplinarian known as “Sour” Crout, played by Lionel Jeffries. His strict oversight and sharp eye threaten to unravel the entire operation, leading to a near disaster that forces the group to improvise one more time. Their route back into the prison is cunningly designed: they slip into a garbage truck scheduled for an early-morning pickup, only to be buried under a rough heap of refuse that could bury their chances as well.
Back inside, the diamonds are hidden away in the Governor’s office, awaiting their moment to leave the compound. The plan falters, though, when the precious cargo ends up scattered along a railway line after a chaotic sequence of events. Stevens is eventually recognized and arrested, but not before Crout’s intervention—an overbearing clash that even results in him throttling an actual Vicar and igniting a tense, almost riotous atmosphere around the prison.
The surviving trio refuse to concede, continuing to chase a second chance to reclaim the diamonds. Disguises, misdirections, and a climate of relentless pursuit propel them toward one final, surreal moment: the group is spotted at a ceremony where the Sultan is to be presented with his weight in jewels, a melodramatic finale that keeps the suspense tight and the tone buoyant. Across these twists and turns, the story remains both sly and comic in its approach, balancing bold capers with character-driven humor and a steady thread of daring ambition. The result is a brisk, entertaining caper that plays out with wit, warmth, and just the right amount of chaotic charm.
