It's crunch time.

"The Walking Dead" returns on AMC for a third season Sunday at 9 p.m. EDT. Millions of fans will be tuned in, ravenous for what awaits the zombie-beset mortals on the first of 16 episodes (eight now and eight more beginning next February).

To appraise the new season (with two episodes provided for review) or, for that matter, to explain the series' appeal is somewhat of a fool's mission: You either get "The Walking Dead" or you don't.

But let's consider its virtues anyway.

'The Walking Dead'
When: 9 p.m. Sunday
Channel: AMC

Like the "Walking Dead" crunch. It's a squishy crunch (or, no less lurid, a juicy thud) that greets the viewer's ear as each zombie is picked off by Sheriff Rick Grimes and his fellow refugees.

Whether it results from a knife's gash, a gunshot or a stick plunged through some zombie's eye, it's a satisfyingly decisive sound that, even without the gooshy image that accompanies it, signals yet another wasted so-called "walker." Just hearing it, the viewer knows to score one for the good guys.

Not that there's any winning this conflict. This, after all, is a zombie apocalypse. The zombies just keep coming.

So "The Walking Dead" is an anomaly among TV series, whose heroes and narratives are mostly aspirational. Not here. The only aspiration for the "Walking Dead" survivors is to survive another day. And that is never guaranteed, as shown by the series' demonstrated willingness to kill off some of its most popular characters.

In short, "The Walking Dead" may be the bleakest TV series ever aired.

Also one of the most leisurely. In the best tradition of suspense-building thrillers, "The Walking Dead" practices, then doubles down on, a meditative pace where tension builds while little is said and not much happens -- that is, until it does.

On the season premiere, Rick (Andrew Lincoln) and his band (including co-stars Sarah Wayne Callies, Norman Reedus, Steven Yeun, Emily Kinney and Scott Wilson) are on the run from their previous refuge, a farm overtaken by zombies months before.

Then they come upon a prison in the Georgia countryside. They plot to take it over from the zombies that infest it. It could prove to be a safe haven against further assaults.

But nothing is simple. Or quick. There's lots of anguished talk and furrowed brows. The episode even makes room for a plaintive lullaby sung over a crackling campfire.

Then, in a burst, plenty happens. There have been "Walking Dead" episodes that shortchanged the viewer with too few zombies on display. And there have been episodes with escalating dread but no dramatic release. This is not one of them. Count this episode -- packed with a zombie skirmish, a terrible twist and a bonus complication -- among the series' most unforgettable.

It's a nightmare you typically handle by waking up. But only if you were asleep. If you're awake, the best way to deal is by savoring the blows to a zombie's head, each certified by a satisfying crunch.