Steve Lopez first stumbled onto Nathaniel Anthony Ayers near a tunnel in Los Angeles, not far from Skid Row. Lopez, a weekly columnist for the Los Angeles Times, was hard up for a column topic, heard an unusually talented street musician in an unlikely place, and struck up a conversation. Articulate, clearly unwell, and doing impressive things with a broken-down violin, Ayers half-intrigues and half-amuses Lopez, who comes back to see him. On his second visit, Lopez notices Ayers scrawling names in the asphalt. "Who are those people?" Lopez asks. "Oh, those are just my classmates from Juilliard," Ayers answers.

Wait, what? That last sends Lopez back to his office to do some Googling and make some phone calls. Indeed, it turns out that Mr. Ayers attended Juilliard as a bass violinist before paranoid schizophrenia drove him out and eventually onto the streets. If the word "Juilliard" means nothing to you, suffice it to say that musicians with the chops to get into the immensely prestigious New York City academy do not ordinarily wind up homeless. Here, Steve Lopez thought, was a column. Maybe a couple. What follows, at least as Lopez tells it in his book The Soloist, is not your traditional inspirational tale. Lopez feels compelled to do what he can for Ayers, but he can only do so much. Ayers is intelligent and kind – but, being sick, is prone to outbursts, paranoid (and sometimes racist) ravings, threats. Readers, moved by the columns, donate musical instruments – but Ayers sleeps on the street and drags around a shopping cart. Where is he to keep a new cello? Worse, Ayers adamantly refuses psychiatric help (he had a bad experience with medication and shock therapy), and won't even consider moving into a room kindly offered by an organization dedicated to helping the Skid Row mentally ill.

Much of the book, therefore, is a nitty-gritty chronicle of the logistical nightmare that is attempting to help a paranoid schizophrenic living on the streets of Los Angeles. Lopez is fortunate in that his L.A. Times clout helps him obtain the necessary resources, but that's maybe a quarter of the battle. Helping a schizophrenic is like helping a drug addict: they have to do a lot of the work themselves.

Lopez is very up front about Ayers's prospects. He will never, at this point, be a virtuoso. He will never join the Los Angeles Philharmonic. Probably he will never hold down a job. No miraculous recovery and triumph here: it's not that kind of story. The best he can hope for is a room in a facility and a place to practice music. Nor is he any sort of Holy Fool: he has no elusive wisdom to impart, at least not directly. He's a good man, we sense, but a deeply troubled one, and no inspirational figure.

All of which is to say that you shouldn't be too put off by this kind of repulsive trailer for Joe Wright's The Soloist, which casts Robert Downey Jr. as Steve Lopez and Jamie Foxx as Nathaniel Anthony Ayers. I'll admit that there's something intangibly obnoxious about Jamie Foxx in the role of a mentally ill violinist, but overall I hope and suspect that the trailer misrepresents the film. While you can probably bet that some of the book's more uncomfortable moments – Ayers' hideously racist rants, for example – won't make it to the screen, I'd be stunned to see an anodyne love-conquers-all fable made from this material, especially by a director like Joe Wright (Atonement, Pride & Prejudice) – and especially since Lopez is supporting the film.

So although Dreamworks has done its damnedest to repel intelligent moviegoers, you should know that the source material, at least, is not maudlin or schmaltzy. The movie, adapted by ultra-mainstream screenwriter Susannah Grant, probably ramps up the earnestness (the trailer alone contains roughly three times as much speechifying about friendship and caring as the book does). But if nothing else it began as a sad, subtly disturbing true story