It could have been a better film. It does drag at points, and the central story shifts from Boyer completing his mission to Boyer avenging Wanda Hendrix's death, but Graham Greene is an author who is really hard to spoil. His stories are all morality tales, due to his own considerations of Catholicism, guilt and innocence (very relative terms in his world view), and the human condition.
Boyer is Luis Denard, a well-known concert pianist, who has sided with the Republicans in the Spanish Civil War. He has been sent to England to try to carry through an arms purchase deal that is desperately needed. Unfortunately for Denard he is literally on his own - everyone of his contacts turns out to be a willing turncoat for the Falagists of Spain. In particular Katina Paxinou (Mrs. Melendez) a grim boarding house keeper, and Peter Lorre (Mr. Contreras) a teacher of an "esperanto" type international language. Wanda Hendrix is the drudge of a girl (Else) who works for Mrs. Melendez. The local diplomat, Licata (Victor Francken) is already a willing associate of the Falangists.
The Brits (Holmes Herbert, Miles Mander, and best - if not worst - of the lot, George Coulouris) don't give much hope to Boyer's cause (which he soon grasps may be Britain's before long). Herbert and Mander just retreat behind the official policy of neutrality ordered by the Ramsay MacDonald's and Stanley Baldwin's governments during the Civil War. Coulouris here is a typical Col. Blimp type - always impeccable in his native English diction, he is sharp in showing his dislike for foreigners in general.
The one ray of hope is Lauren Bacall (Rose Cullen), here trying to play her role as well as she can - but she can't really. She's an aristocrat - the daughter of a Press lord. It was Bacall's second film, and (sad to say) almost sank her long career. She does act well, but the spark she showed in her first film was due to the dual effect of starring with Humphrey Bogart and being directed by Howard Hawks. Boyer is a fine actor, but he's not Bogie, and Herman Shumlin is not Hawks. Her next film returned her to Bogie and Hawks again, and her star resumed it's ascendancy.
It's a bleak film (as was the novel). Boyer's mission never succeeds, as he has too many hidden foes all over the place. But the villains are likewise also losers - frequently with their lives.
With Dan Seymour as a suspicious foreign tenant of Katina Paxinou (and the man who destroys her). It is well worth watching to catch the Warner's lot of character actors doing their best given the weakness in direction.

I just saw DreamGirls yesterday, and I was REALLY underimpressed. Despite all the Oscar buzz, this is nothing special. Anyone who was really impressed by this film has never bothered to see any of the true movie musical classics. Except for Eddie Murphy's great musical and dramatic performance, Dreamgirls is just a glorified TV movie with no style or flair. Just a bunch of amateurs singing AT each other!
Now, the first half hour was good, but I was irritated at how Eddie Murphy's terrific raveup performances were truncated and interrupted by montages. Those were easily the best songs and best performances in the film. And the "rise to the top" portion of the film was the only part of the film that had a consistent point of view or any momentum. The remaining hour and 45 minutes was a formless, rambling mess that was neither realistic nor fantastic enough to be interesting. It was also visually dull and included too many sound-alike tunes.
Condon didn't try to turn any of the tunes into big show pieces as I'd expected they would. Each number in the 2nd half was just one closeup after another of people "singing" AT each other. And the way they shot Hudson's big "love me" number was criminal! Condon just shot her stomping around the stage--no drama at all! God it sucked!
AND note to all involved--that "sing-talking dialog" stuff might work on stage, but it DOES NOT WORK IN MOVIES (see embarrassing failures of Evita and Phantom). All that "I'll teeeell youuuu something Efff-ieeee!" crap should have been left on the editing room floor. Those aren't "songs."
Again, the film--except for Eddie Murphy's amazing performance--was nothing more than a glorified TV movie. There must have been megabucks behind the PR work for this film! I wonder how much money was spent to give it that pre-release "one to beat" Oscar buzz? As a whole this film was, except for Eddie, NOWHERE NEAR an Oscar caliber movie! (except for Eddie) I'd rank it right up there with Grease 2. BIG disappointment, especially after all the (very expen$I've) hype!