The more movie gangsters change, the more they stay the same. In the 1930s they were Irish (The Public Enemy) and Italian (Little Caesar, Paul Muni’s Scarface). Since then, the hoods have become Jewish (Bugsy, Once Upon a Time in America), Cuban (Pacino’s Scarface), and African-American (New Jack City, American Gangster). It’s the ethnicities that change while the sociology stays the same. With the important exception of The Godfather, which posited one big, temporarily happy family operation, the gangster is portrayed as the product of a home stymied by poverty and joblessness. So a boy takes to the street because the street offers work—illegal but profitable—and, perhaps more important, self-respect. As the hero proves his manhood to his peers by acts of extortion and murder, his partners in crime become his real family.

Nowadays, as movie gangsterism moves to South Africa (Tsotsi) and Brazil (City of God), the formula recurs: the hero feels he must be true to “the hood” and to his brothers-in-violence with their warped but adamantine codes. Then something happens to tempt the hero away from gang life: in Tsotsi it’s a lost baby, in City of God an unexpected artistic vocation. In the new American Spanish-language film sponsored by the Sundance Institute, Sin Nombre, the temptation is more familiar: a criminal youth’s pity for, and growing attraction to, a pretty girl down on her luck.

The plot begins on two separate tracks that eventually converge. A middle-aged Honduran who has found a niche in New Jersey (albeit illegally) comes back to his native country to fetch his daughter, Sayra, and his younger brother. Their journey into the States depends on an illegal train route. Meanwhile, we meet Casper, a member of the Mara Salvatrucha gang in Mexico (apparently the gang’s real origins are Salvadoran, though its membership has gone international). He is always ready to kill at the behest of his chief, Lil Mago, but reveals a tender side with his nongang girlfriend, and also shows trepidation about initiating a little boy, Smiley, into the Mara way of life. So this young brute is redeemable, right? And we know from the start who will redeem him. Otherwise, why would we have been introduced to Sayra and her plight? But what about his current girlfriend, who has already touched his humanity? Are there to be two heroines in the plot?

Well, that’s the first clank we hear in the machinery of the plot. The girlfriend must be killed by Lil Mago during a rape attempt, but Casper’s inevitable revenge can’t take place until he and Lil Mago are aboard the train on which Sayra is riding with her father and uncle. The gang bangers are there to rob the passengers, but when Lil Mago attempts to rape Sayra, Casper dispatches him. By this time, you may begin to suspect that all incidents dreamed up by first-time writer-director Cary Fukunaga exist for the sake of the melodrama, and that there are not going to be any interesting side trips or detours.

And so it goes. Since Fukunaga wants Sayra and Casper to be sweethearts on the run, he must get the two of them off the train. Believably enough, Casper jumps off before he gets to the border in order to hide himself from the gang’s vengeance. But then Sayra jumps off, too, in order to be with him. It is the act of a high-flying romantic, like Shakespeare’s Juliet or Manon Lescaut or, at least, Bonnie Parker. But the script has portrayed Sayra as down-to-earth, recalcitrant, cautious; and the manner and looks of the actress who plays her, Paulina Gaitan, are placid and utterly devoid of passion. We can believe her gratitude at being rescued from rape but not this sudden flight into the unknown with a stranger. Yes, I know that still waters run deep, but it is the dramatist’s job to give us a premonition of those waters before they turn into a whirlpool. Fukunaga is opportunistic in his depiction of emotion. Love and hate, compassion and sadism: all are just items to be checked off on his to-do list as he moves the plot along.

The early scenes of gang life hold our attention not because they are freshly observed or excitingly done but because it’s hard to make brutishness and violence boring. Those tattoos...those shaved heads...the chopped-up corpse of an enemy plopped into a pail and fed to—gag—a dog. But once Casper and Sayra are on the run, and the violence is temporarily suspended until the final showdown, the only thing that can grip us is the characterization of the young couple as they get to know each other. And it’s precisely here that the movie runs aground. As Casper, Edgar Flores broods convincingly and Ms. Gaitan’s eyes convey an air of beset purity. But neither possesses the sort of emotional range that would lift them beyond the generic roles of young lovers and martyrs.

To be fair, there is one remarkable scene. Smiley, who can’t be more than twelve, is drafted into the gang’s hunt for Casper. Even though the latter has been the boy’s pal and mentor, Smiley is exhilarated to be included in Mara business. When he boasts of his promotion to some even younger children, these eight- and nine-year-olds receive the news as if they were hearing of a chum making the local soccer team; they even advise Smiley to find a way to ambush Casper. Life for them has no more weight than an interactive video game. They offer a seemingly inexhaustible supply of new members to the Mara. In this single scene, Sin Nombre comes to shocking life.

Duplicity aspires to nothing but movie-movie life, and that would be fine with me if only I weren’t left with such a brassy taste in the mouth and a sense of pseudostimulation in the mind. Tony Gilroy’s second film (the first being the excellent Michael Clayton) was written (by the director) and edited (by his expert brother, John) to yield the same pleasure that a jigsaw puzzle gives. But why not buy a real jigsaw puzzle and put it together yourself rather than have moviemakers assemble one for you?

The film’s main interest for me was in its demonstration that the new industrial-espionage movie genre, which was supposed to replace the conventional ideologies-in-conflict stuff at the end of the cold war, probably won’t flourish after all (especially now that terrorism has introduced new ideologies in collision). True, Duplicity contains many of the old features: glamorous locales, chases, hairsbreadth escapes, handsome male and female agents matching wits and locking loins. But what’s at stake? In anti-Nazi and anti-Communist thrillers, the fate of nations was supposedly at hazard, and this lent urgency even to the doings of a sybarite like James Bond. (He is our sybarite.) The espionage thriller is but a subgenre of melodrama, and melodrama needs a hero. When it’s a matter of greedy spies working for, or perhaps double-crossing, two greedy rival tycoons, as in Duplicity, for whom do you root? To be sure, Gilroy seems to think that his real theme is trust. Can his spy-lovers trust each other when their real talent is for deception? “Would it make any difference if I said I loved you?” sighs Julia Roberts at Clive Owen, to which he replies, “Would it make any difference if I said I believed you?” To which I mentally screamed, “Who cares? You’re both in love with money and you know it!” And since, in this age of Bernard Madoff, they’re trying to steal millions instead of billions, they come across as pikers.

Could it be that Gilroy thought audiences would accept the substitution of movie-star glamour for characterization? Well, Roberts smiles her usual mile-wide smile and the new, spruced-up Clive Owen sports his expensive duds and haircut with élan, yet the two don’t quite click. Their looks click, the way certain models look good together in a fashion shoot. But when actors achieve that much ballyhooed thing, on-screen chemistry, it’s as if we’re seeing not merely personalities meshing but two different pasts, two different worlds, sliding into harmony. In The African Queen, Katharine Hepburn and Humphrey Bogart, nearing sixty, with faces lined and sagging, struck more sparks off each other than the sleek pair in Duplicity can. Even movie stars need stories, not just maneuvers. Watching Roberts and Owen walk through this soulless script with soulless competence, I couldn’t help wondering if the real chemistry wasn’t between the movie’s producers and the actors’ agents.