It's sadly not uncommon for a good show to fade as it ages. It happened to Lost, to Six Feet Under, even to The Wire. What's rare is a show that's five or so seasons in and is the best it's ever been. But, much to our surprise, that is what's currently happening on CBS's The Good Wife, a show that is not just back to form after a fourth season slump, but is delivering the best drama on network television. Trouble is, it might not be sustainable.

I know that people are probably sick of TV critics and the like harping on about how you should be watching The Good Wife, but in this particularly dire new television season it's worth reiterating that there is cause for celebration amidst all the despair. (On CBS, no less!) And anyway, the once-persistent rallying cries probably died down some last year, as the show became mired in some go-nowhere plots and critical support began to evaporate. But now it's back! So here's yet another urge to tune in. (Or catch up: CBS.com has this season's first five episodes here.) Sunday nights are busy, yes, but at the moment, The Good Wife is more engaging, artful television than The Walking Dead, Homeland, or any of its other prestige cable competition.

[Are you planning to take our advice and start watching the show? Good! Now stop reading... spoilers abound.] 

But back to that unsustainability problem. The reason the show has been so good lately is that it's burning everything to the ground. Our serenely melancholy heroine Alicia Florrick has left Lockhart/Gardner, the firm that's been the centerpiece of the show since it began. Not only that, but her frenemy Cary Agos has gone with her too, taking a bunch of fourth-year associates, and a number of top clients, with them, the intention being to start their own rival firm. This was all behind Will Gardner and Diane Lockhart's backs, of course, meaning it was not just leaving a job to start something new, it was a betrayal. And last night's episode, titled "Hitting the Fan," was when the plot was uncovered, Lockhart/Gardner going into full survival mode and the traitors scrambling to take whatever client wasn't nailed own. It was breakneck television, snappy and fast-paced and morally ambivalent, proving that no violence is needed to craft an excellent thriller. The build-up to this moment, meaning this season so far, has also been edge-of-your-seat entertainment, moving with a nimble, witty dexterity rarely found on TV, especially 22-episodes-a-year TV. So yes, The Good Wife is humming right now — as legal thriller, as romantic drama, as arch pop culture comedy — but what happens now?

The break with Lockhart/Gardner seems, for the moment anyway, to be pretty definitive. Alicia's relationship with the firm (and furious, heartbroken Will) is in ruins, and she's got her governor-elect husband throwing his weight around in ethically dubious ways to help her. It's hard to imagine a future in which the original team is back together again and working (semi-) harmoniously. So is The Good Wife irrevocably different now? It might be! And while that's been exciting to watch, I worry that a fundamental altering of the show's basic structure will eventually prove a detriment. Hasn't that proven true in the past? While it provided a couple of cool "oh my god" moments, Lost's lurch into the future, and out of its traditional island/real world flashback schema, ultimately undermined the whole endeavor. The minute that Dexter bared his true nature to someone, the potency of his secret was diluted. (Leading to the eventual, though seasons-away, downfall of the series.) The Good Wife is more of a procedural, and thus might not suffer as much under a radical structural change. But now that the show has pulled of its biggest ta-da trick yet, it seems likely that we're headed for some kind of slump, or at least a plateau. Which is too bad.

According to the series's creators, the next three episodes, called "The Next Day," "The Next Week," and "The Next Month," will wade through the fallout of the big Lockhart/Gardner vs. Florrick/Agos rupture, which ought to be interesting. But what then? Much as Game of Thrones might have trouble staying exciting in a post-Red Wedding world, will The Good Wife be as enjoyable now that the show's simmering volcanic drama — Alicia the lawyer's relationship with the firm, Alicia the woman's relationship with Will — has erupted? Well, of course we know that crazier things than an amiable reunion have happened on television. So maybe the show will find its way back to something resembling its original shape. But for the time being, the show's biggest moment yet has come and gone in spectacular, expertly calibrated fashion. And what a thrill it was! Let's just hope they can keep the momentum going, and that The Good Wife hasn't grandly shot itself in the foot.