While these stories arise from sober and recognizable threats — nuclear war, plague, climate change, resource depletion — these serve as little more than a trigger for the plot, which involves handsome actors going postal on the relevant villains: aliens or cyborgs or, more recently, zombies meant to personify the dehumanizing effects of modern society. (They’re mindless consumers who stagger around in search of gratification — get it?)

If this sounds reductive, take a peek at the highest-grossing apocalyptic films. Nearly all of them, from the Terminator franchise to “The Book of Eli,” adhere to this Mad Max formula.

The Children’s Crusade

It’s only natural that the apocalyptic canon has radically expanded in the past few decades. Never has our species been so besieged by doomsday scenarios. If our ancestors channeled their collective death instinct into religious myth, we now face a raft of scientific data that suggest the end might be truly nigh.

This may explain the most perverse trend to yet emerge in the genre: child heroes. The exemplar here is “The Hunger Games,” which is about a girl who participates in a gladiatorial contest against other kids for the entertainment of a debased population. Most of the film is devoted to watching Katniss Everdeen become a trained killer and engage in combat. A sequel will be coming out in November, right on the heels of “Ender’s Game,” which features an exceptional child who is transformed into a super-soldier and fights off a horde of aliens. The recent Will Smith vehicle “After Earth” offered a father-son variation on this theme.

My hunch is that films of this sort, in addition to bringing a younger demographic into the fold, appeal to the particular anxieties of parents raising children in such a fragile and fearful age. The message is supposed to be one of empowerment: Don’t worry, our kids are stronger than we think. And yet, as I watched Katniss being put through her lethal paces, I couldn’t escape the sense that her story had a more ominous moral. Forget about teaching the kids to be more empathic or to garden vegetables. If you want to rescue them, turn them into secret weapons.

Faced with the specter of militarized minors, I found my mind drifting back to “Childhood’s End.” In Clarke’s version of the apocalypse, the children of Earth don’t ape the savagery of their parents. They prepare for the next stage of human evolution. This requires them to lie still, eyes closed, and communicate through telepathy until they’re absorbed into the supreme Overmind. There’s something profoundly humble in this vision of peaceful surrender and ascendance. The loss of individual identity becomes a kind of necessary sacrifice.

I also couldn’t help taking another look at “The Day After.” I was astonished to discover how wrenching it was. The scenes devoted to the nuclear attack are genuinely horrifying. Despite occasional lapses into melodrama, the grief and bewilderment that prevails among the survivors feels real. There’s not a single villain or mercenary and no one to save the day. The only heroes are the people who perform small, noble acts in the midst of wretched circumstances. The emotional fallout of the story is the opposite of today’s apocalyptic thrill rides.