The High Commissioner finds Rod Taylor playing as is native Australian for once on screen. He's an Australian cop who is pulled off regular duty by the Prime Minister of New South Wales played by Leo McKern and asked to arrest the Australian High Commissioner in London on an old charge of murder. The High Commissioner is Christopher Plummer and the victim was his first wife who died under mysterious circumstances.
It's pretty obvious to Taylor that McKern has a political agenda and Plummer is an old rival of his. Even though this extradition seems to stink on ice, Taylor does have a job to do.
Once in London there is an attempt on Plummer's life that Taylor foils and Plummer is involved in some high level negotiations with non-aligned countries that someone doesn't want to succeed. We're left pretty much in the dark as to exactly who so our imaginations can run the gamut from the Communists to some Ian Fleming type entity like SPECTRE.
The women in this film are something to see. Plummer has a devoted second wife in Lilli Palmer who would do anything to see her husband succeed, ditto his embassy secretary Carmilla Sparv. The bad girl here in the story is alluring and mysterious Daliah Lavi who runs a gambling house in London. A lot of secrets are traded here as this seems to be a kind of neutral ground in the Cold War. Lavi was one of the sexiest women of her time back in the day and she's enough to lure people back from the dead.
This film with a brief appearance in a hospital bed from Franchot Tone was his farewell role. This could have been a real hospital bed because Tone didn't look too good. A sad farewell to one of the screen's most debonair players who was always fighting for roles to display his acting rather than good looks and sense of style.
One other role that does have a sense of style involved is that of Plummer's butler Clive Revill. He finds Taylor's Aussie ways somewhat uncouth, but Revill has more to him than a sense of manners.
The High Commissioner although somewhat murky is a fast moving action flick with a surprise ending and yes as another reviewer says, similar to Alfred Hitchcock's Sabotage.