Barnard fills out this subculture with a journalist's eye. The light, the soot, the fog, the way sun hits the sides of buildings, the subtitled slang-riddled dialect, the posturing, the moments of ribald humor and casual bullying, the offhand exploitation of children and horses, all bespeak great powers of observation. Barnard sometimes films the boys in long shot. They're flyspecks inching along cracked pavement and weed-strewn fields, industrial northlands looming behind them. Even when these images are used for rhythmic purposes—to give the eye a chance to breathe between bouts of close-up camerawork—they're never purely pictorial; they're putting the boys and their story in a larger context.

A low-speed chase between rickety horse carts has a nerve-wracking physicality. In a time of CGI-driven filmmaking, even the most epic action has little dramatic or figurative weight. This is, no matter what safety precautions were taken, an actual event. You worry about the horses and riders who are being followed by a carloads of drunken spectators and bettors, a soused peanut gallery on wheels.

The filmmaker shows how the metal is collected and haggled over, and the personal and economic factors that affect scrappers' and buyers' survival. The viewer may be reminded of the borderline-slave economies of the early 20th century American economy, before the unions settled in. Just as a 1920s miner was docked for his clothes, tools, room and meals, and came to feel as though he were working for the privilege of being allowed to live, the scrappers' game is rigged against them. In time, the junkyard horse seems analogous to the humans it serves: a beast of burden valued only for the weight it can bear.

"The Selfish Giant" may remind you of other films about childhood under harsh circumstances, none of which, to put it mildly, were upbeat: "Killer of Sheep," "Sounder," "Los Olvidados," "Panther Pachali" and "Kes." It's not on the level of those inspirations—its doom-spiral story feels contrived in places—but there's no denying its effectiveness. The film is a tragedy: keenly observed, warm, often funny, but a tragedy. And yet even when the life-on-rails dramaturgy becomes wearisome, we feel we're watching an evil adult exploit angelic children. Arbor and Swifty aren't "good" or "bad" boys, just desperate and far too trusting. Kitten isn't a villain, just a mangled product of his environment like everyone else.