Director Michael Winterbottom (24 Hour Party People, The Claim) and his frequent collaborator, screenwriter Frank Cottrell Boyce, assume a lot on behalf of the audience, like that we don't need everything explained to us, that we'll catch on to what we need to catch on to and appreciate the rest as hints of a larger, fully realized world we're simply not seeing all of. This isn't the filmmaking school of "Oh, hey, it's the future because everything is shiny and neon-y," this is the school of "Let's tweak everything just a little bit and see what happens." So we get vast, prosperous Shanghai... full of people of all colors and ethnicities, where everyone says "Salam" for "Hello" and speaks in a patois of English, French, Spanish, and a dozen other languages (none of it translated or subtitled for us, and we don't need it). We get vast, prosperous Shanghai... where access to the city is tightly controlled, entry granted only through a checkpoint outside of which desperate throngs wait for permission to enter that will never be granted. We get vast, prosperous Shanghai... where citizens stay hidden indoors by day and venture out only at night. Has the sun become dangerous? Is pollution worse during the day? Is the problem the dust from the surrounding desert? All or none of the above? It doesn't matter. It makes for a scarily plausible near future, because we see the beginnings of it all in the here and now.

All these things, of course, are only part of the mere background, totally uncommented upon, in the seemingly simple story of William (Tim Robbins: Mystic River, The Truth About Charlie), a criminal investigator, and Maria (Samantha Morton: In America, Minority Report), his prime suspect in a forgery case. She works for Sphinx, the global papelle manufacturer -- papelles are the passes, the "cover," citizens need to travel outside their home cities -- and William believes she is the source of the faked papelles that have been causing unexpected trouble. But, in grand film noir tradition, he falls instantly in love with her and does not turn her in to his superiors. The mere-background, uncommented-upon, SF twist is that his infatuation may be the result of his heightened emotional sensitivity, one of the genetically engineered tools of his trade. Genetic engineering is part of the mere background, too, as is cameras-everywhere security and a cradle-to-grave nanny government... until, suddenly, none of it is part of the background anymore, and Winterbottom and Cottrell Boyce's subtle genius conflates it all, bringing everything together to subvert the expectations of both the philandering-husband love story and the SF thriller, giving us an extraordinary film that is one of the best of the year.

But even if all you wanted was a romance, never mind the science fiction, Code 46 would have enough to offer. William and Maria's brief affair, illicit for reasons beyond his marriage, is the story here, and it's been ages since I've seen an onscreen couple with the chemistry of Robbins and Morton. William and Maria sizzle together with the urgency of desperation, making the film as sexy as it is cerebral.

Add that to the sexiness that "cerebral" already has to start with, particularly for fans of the brainy kind of SF Code 46 is, and... wow. Just... wow.