Recently I became what almost felt like the last person in the English-speaking world to read Jonathan Franzen's latest novel Freedom originally published last summer and now out in paperback. This terrifically ambitious saga stretches forwards and backwards from the central, fraught relationship of Walter Berglund and Patty Emerson, a liberal couple who first meet at college in the late 1970s. From this starting point, Franzen manages to create a colossal picture of 21st-century America: its history, its popular art, its corporate culture, its homeland insecurity and its endangered natural world.

Now, there can hardly be anything left to say about Jonathan Franzen and his place in literary history. But I think it might be possible to note the way he could be changing the course of film history. Single-handedly, Franzen might yet restore the reputation of the Greek film-maker, Nikos Koundouros.

Lovers of this novel will know that for their very first date, Walter takes Patty to a movie. Somewhat heartsinkingly for the unpretentious and sporty Patty, it's a black-and-white film from the 50s, being screened free of charge at the University's Art Department auditorium, a grim indication that it is not going to be much fun. Its English title is The Fiend of Athens and as she remembers it (the event is actually recounted by Patty in the therapeutic journal she is writing later) the film is about a mousy, timid, bespectacled guy in Athens who sees a newspaper photo of a fugitive criminal mastermind called "The Fiend". It's the spitting image of the harmless nerd.

A gang of starstruck crooks sees our hapless hero, mistakes him for the Fiend, rescues him from imminent arrest and more or less forces him to lead a desperate criminal scheme they've got going. And finally, the poor little man becomes enamoured of the idea, decides for once in his sad life to be a tough guy and a hero. He surrenders to his bizarre destiny, to be The Fiend of Athens.

Later, the couple argue about what the film means. Walter sees it as a political parable for the fightback against right-wing oppression. Patty sees it as a purely personal story about masculinity and taking action. Later in the book, there is a chapter called The Fiend of Washington. Walter, like the film's protagonist, has decided to flex his muscles a little and throw in his lot with some corporate alpha-males.

Originally entitled O Drakos, or The Dragon, the film was made by Koundouros in 1956 and played at the Venicefilm festival; it earned Koundouros a reputation as the "Orson Welles of Greece" and was accounted one of the most important films in Greek cinema. Nonetheless, sadly, many official histories of world cinema pass over Koundouros in silence. That could all change. Since the publication of Franzen's Freedom, interest in this movie has been steadily growing. People are keen to see it. But finding a subtitled print or DVD is far from easy. Christos Prossylis, the director of the forthcoming London Greek film festival, tells me he has recently paid a personal visit to Koundouros, now a vigorous 85 years old, asking for permission to show a subtitled print at the festival. He reports that Koundouros is delighted at the resurgence of interest in his masterpiece, but he has no English subtitled copy, and there are other rights issues.

However, the Greek film writer John Stylianou has posted the film in its entirety on YouTube and put on English subtitles himself.

It is a massive labour of love, and we should all be grateful to him, because O Drakos is brilliant: a dark, satirical noir masterpiece. Patty's description doesn't do it justice. Yet that could be the point.

The Dragon is like a French New Wave picture crossed with a British Ealing comedy, with something of Fellini in its zinging energy, and Carol Reed's Odd Man Out and The Third Man. The stark, dramatic key-lighting in the "arrest" scene gives the imagery a Weegee-type crime-scene aesthetic.

And it actually turns out to be interestingly different from the film that Franzen's Patty remembers. The differences provide a telling slant on the action of his novel. Could it be that Franzen intended readers of his book to go out and watch the film, and notice the difference … a time-bomb of added meaning, buried deep in the text?

Patty says that the mousy anti-hero (whose name is Thomas, played by the actor Dinos Iliopoulos) finally makes a dramatic decision to go along with the illusion, and she gives the impression that the crooks are fooled by his resemblance to the fabled master-criminal. In fact, if you watch the film, you'll see that isn't the case. His decision isn't quite as clear cut as that, and at least some of the crooks know well that he is not "The Dragon". But they need The Dragon's prestige and street-cred to bolster their dodgy scheme – to steal Greek antiquities and sell them to shady American collectors. In fact, they may well be nervous about Thomas spilling the beans and this could account, partly, for the bizarre violence at the weird pre-crime party at the end of the film.

The criminal brotherhood has an ambiguous relationship with poor Thomas, to say the least, which mirrors Walter's calamitous association with a rightwing mining corporation. Was Patty aware, from the very beginning, of how her earnest beau might some day wish to assert himself, and how that might turn out? Did she suppress the film's meaning?

Whether or not you have read Freedom, The Dragon is a tremendous film, and Koundouros fully deserves the upswing of interest. Perhaps Criteron can be persuaded to bring out a definitive DVD edition. Meanwhile, Prossylis says that the London Greek film festival is scheduling a showing of Koundouros's 1992 film Byron.

• More information on the London Greek film festival