The “Purge” movies — of which there have been four so far — make for an appealing morality play. They depict an America in which all criminal impulses are expiated during twelve hours during which all crime is legal, a state of affairs whose illogic is practically the point. It’s not meant to be believable, really, but it’s meant to spark realistic responses from characters we can cheer or boo, and to create the opportunity to rack up increasingly grotesque kills.

Those two guiding principles of “The Purge” franchise — using a lawless environment to create sympathetic situations for likable characters, and piling up bodies killed gruesomely — collide once again in USA’s new TV adaptation. This limited series follows various players in an annual Purge, including a couple who drop in on a party for the well-heeled, who spend the Purge safely ensconced and celebrating evil; a corporate partner on lockdown, closing a deal and watching her coworkers decompensate; and a death cult whose members, parked in a bus swarmed by Purge participants, happily allow themselves to be murdered.

If there’s one story we’re meant to follow most closely, it’s probably that of Miguel (Gabriel Chavarria), a Marine searching for his sister (Jessica Garza). She’s checked herself out of rehab and joined up with the show’s cult, heading towards her oblivion. We see other cult members, in sequences that derive their power from their willingness to embrace schlock, stepping off the bus and being brutally hacked to pieces; the camera cuts away before viscera are exposed, but it’s horrific all the same. To save her from this fate, Miguel runs through a violent gauntlet in which he, too, must take lives. It’s a web in which the problem of violent death can only be solved through the solution of violent death, a closed-ended system with just enough imagination to keep us hanging on but not enough to truly surprise us.

After all, the central thread of this story is its most simplistic: Miguel is a good person, on a mission to rescue his sister, a good person suffering through the trauma the family suffered in an early Purge. They’re white-hat heroes, and as flatly uninteresting as the title implies. Other elements of the story bring in enough ambiguity for core fans to stick with this series to its conclusion: The office worker (Amanda Warren), ensconced in her office, has paid a member of the Purge’s shadow economy to carry out a hit, and the married couple at a glamorous party (Colin Woodell and Hannah Anderson) are effectively impostors seeking to soak the pro-Purge elite for investment cash so that they can build low-income housing. Again, their virtue makes for an unfair fight — in the current climate, simply taking money from the rich to enrich oneself makes for an interesting enough motivation — but both partners here, at least, get shades to play other than pure heroism.

It’s in this last story thread that “The Purge,” having been given a TV season’s worth of time to spread out, makes its most effective grasp for the viewer’s sympathy; these people, basically moral individuals in over their heads in an unfamiliar situation, are as naive about the Purge as we are. It’s also where the show attempts to make its sharpest points. The upper-class of this fictional America are vociferously in favor of the Purge, because of its tendency to enforce the existing social order, its effect of eliminating members of the underclass, and what the creepy rich seem to see as the pure fun of murder. It’s a point the show makes with suitable horror-movie unsubtlety. (This show could hardly be accused of forgetting its roots.) It’s a system that, crucially, no major character on this show supports but all have, to one degree or another, learned to live with. At moments, as a couple in rented finery make their way through the sneering killers of the bourgeoise, a more ambitious show winks through: A horror story of the proletariat, one in which strivers and those muddling through fight over the limited resource of life itself.

But how seriously can we take “The Purge’s” critique of class division when the series so garishly embraces the very thing its monsters do, too? The rich, in this universe, are evil for creating a system that glorifies death and fueling it with the bodies of the poor; we look at them in horror, and then thrill to the deaths they catalyze. Their catharsis is ours, too, and the thing that keeps “The Purge” from becoming the great bit of social horror it seems to be striving towards is how painfully underthought the relationship between subject and viewer is. In the show’s first three installments, there are thrills, shocks, and plenty of approbation for the fictional universe’s bad guys. The audience is never implicated; peeking out from behind our fingers from the safety of our couches as the violence amps up, we’re meant to enjoy it all.

Drama: USA. (10 episodes, three reviewed.) Premieres Tues., Sept. 4. 

Cast: Gabriel Chavarria, Hannah Anderson, Colin Woodell, Amanda Warren, Jessica Garza, Lili Simmons, Lee Tergesen, William Baldwin, Dominic Fumusa, Fiona Dourif.

Executive Producers: James DeMonaco, Jason Blum, Michael Bay, Brad Fuller, Andrew Form, Sebastien K. Lemercier, Thomas Kelly, Anthony Hemingway.