I took myself out for an early supper a few days ago. A little family-run Japanese restaurant on the Upper West Side of Manhattan, filled with neighborhood parents too tired to cook, kids with their homework spread out amid the platters of sushi.

Midway through my meal, the place was robbed. Two skinny kids, no more than 15 years old, had come in and, while the waitress’s back was turned, seized the cash box and fled, with five of the staff pounding after them, to no avail.

It was very quick, very unnerving. The speed with which it happened gave it a surreal quality, like a Disney cartoon where naughty boys steal pies while the baker chases in vain, throwing hot cross buns. Fists were shaken, but no weapons deployed. No one was injured. The police weren’t even called because, as the maître d’ explained with a shrug, there wasn’t a lot of cash; it’s a mostly credit-card business.

So life continued, shaken but not substantially stirred. People returned to their meals, children settled back to their homework, and the place resumed its soft murmured conversations amid the tinkling of spoons, glassware, crockery.

Still, there was a restless current of adrenaline that lingered for a while. An understandably distressed mother at the table next to mine described the thieves to her son as “those horrible people.” But as she went on, her indictment of “those people” became an infinitely expanding universe of horribleness, extending far beyond the two who ran off with the till.

Her handsome boy of only 5 or 6 began to muse aloud about what he’d do if he ever caught a robber. His piping little-kid voice carried well as he cheerfully imagined the pain he’d inflict. He’d clearly thought this through, and when he mused about boiling entrails and how you have to drain the blood before you put the severed head on a pike, I was impressed. The detail seemed delivered across centuries, evoking the great English jurist William Blackstone’s eloquence upon the punishment for high treason:

“(1) That the offender be drawn to the gallows, and not be carried or walk…. (2) That he be hanged by the neck, and then cut down alive. (3) That his entrails be taken out, and burned, while he is yet alive. (4) That his head be cut off. (5) That his body be divided into four parts. (6) That his head and quarters be at the king’s disposal.”

As much as the robbery itself, it was the little boy’s gothic soliloquy, delivered in the present tense, that unsettled me.

The unease stayed with me while I finished my soup, then paid for my meal, then walked a few blocks north to drop in on a book party.

The affair was to mark the publication of Nell Bernstein’s Burning Down the House, a comprehensive examination of juvenile detention in the United States. The lack of drawing and quartering notwithstanding, the little boy in the restaurant had been otherwise spot-on about the sort of violence visited on juvenile wards by adult guards and staffers.

Forty-two out of fifty states have extensive, documented records of systemwide maltreatment of minors. From New York to Mississippi to California to Illinois, kids are not just beaten up, not just chained or hog-tied or strip-searched, but subjected to bizarre tortures: in Mississippi, forced to eat their own vomit; in California, to kneel for two weeks, hands cuffed behind their backs without toilet breaks and with only three of every twenty-four hours allotted for sleeping and eating. All over the country, children spend weeks and months in solitary confinement. They suffer concussions at the hands of staff, broken bones, ruptured organs, burst eardrums. And they die—as when a 300-pound guard in Florida decided to sit on a sixty-five-pound child. One in ten incarcerated minors will be sexually assaulted by a staff member.

Up to 90 percent of teens admit to doing something that’s against the law, whether smoking a joint or being truant from school. But only certain kinds of kids are punished. In New York City, 94 percent of children in state custody are kids of color. The majority of these children are behind bars for nonviolent behavior, like running away or drinking alcohol. Yet this disparity remains nearly invisible to those who haven’t experienced it. Fifty-one percent of whites believe that white and black citizens are treated with equal fairness by law enforcement, while 70 percent of blacks sincerely beg to differ.

So there I sat at the party, listening to Nell Bernstein show that the little boy’s plottings in the restaurant were less fanciful than they sounded. Who are “those people” in Bernstein’s account? Sometimes the children involved have been shunted among too many foster homes or have emotional problems. They include abandoned and abused kids, or kids who have been raped and trafficked. Sometimes they haven’t done much of anything wrong, but come from high-crime areas where the police have concentrated their stop-and-frisk superpowers on small “quality of life” infractions. They might have unpaid warrants, issued for riding their bike on the sidewalk or having a dusting of marijuana on their person. Sometimes they are just… nothing more than children, whose scuffles and back talk led not to being scolded or benched from the team, but to being punched in the face by public servants.

There is a vast gap between the dangerous white child, whose lawyerly loquacity elaborates the violent punishment he would mete out to “those people,” and the dangerous black child for whom there is no sufficient language with which to make a claim for his existence. Back at the book party, an astonished guest asked, “Isn’t this illegal?” Bernstein responded, “Of course. And when those kids who are in for having a joint get beaten and raped by their keepers, they learn that it isn’t about what they’ve done. It is all about who they are.”