Benedict Cumberbatch stars as Greville Wynne, a real-life British engineer and businessman recruited by MI6 because of his regular travel to Eastern Europe. Wynne subsequently becomes a courier who transports top-secret information to London from Soviet agent Oleg Penkovsky (Merab Ninidze) during the early 1960s. 

Cumberbatch is often his usual awkward self in this film and when the intelligence services see his business as the perfect cover for their illicit missions, he dutifully steps up. But he keeps his true intentions from his loyal wife (Jessie Buckley as patient Sheila Wynne).

In order to gain intelligence about Soviet missiles being transported to Cuba, his multiple trips start to attract attention and his surveillance tasks become increasingly dangerous. The gentle Englishman is placed into precarious situations which begin to take their toll, not just on his own life but that of his wife and child.

Yet despite their safeguards, the two spies are investigated themselves and finally caught by the authorities and charged with treason. Whilst Penkovsky admits his betrayal, he attempts to protect his double-dealing ally by claiming Wynne knew nothing.

The final act delivers a more demoralising tone with Cumberbatch embodying – or changing his body into – a husk of a human to reflect the meagre resources in the strict Siberian prison he’s sent to. It’s a real gut punch that contrasts starkly against the more regular Cold War drama sequences seen up until to this point.

He does a convincing “Bale” to physically capture an inmate’s emaciated state, becoming a hollow and broken man. Yet, he plays Wynne well with a sort of stoic soul, perhaps the only way anyone could ever get through the inhumane treatment he faces.

Some may know the true-life tale but it’s not dissatisfying to discover the story ends mostly on a high rather than a low conclusion. The film illuminates a little-known, but hugely important, aspect of history where one man’s individual strength became the catalyst that prevented possible global conflicts.

Audiences therefore should definitely take a snoop at The Courier. As although it’s not a game-changer, it’s a great espionage drama with a terrific Cumberbatch central performance as a small-scale man hiding big-time secrets.