"World War Z" could have been the Amanda Bynes of summer blockbusters.

It would have been so easy for Brad Pitt’s troubled zombie epic to hide out under a series of ridiculous wigs, insisting to the world that everything was fine and tweet-hating on anyone who tried to help.

But rather than keeping quiet and fleecing moviegoers as yet another saw-it-coming-from-a-mile-away dud — here’s looking at you, "After Earth" and "The Internship" — "World War Z" admitted it was a hot mess and sought help.

Director Marc Forster ("Quantum of Solace") had finished shooting the script Matthew Michael Carnahan ("The Kingdom") based on Max Brooks’ novel — or, more accurately, based on its title. There’s very little resemblance.

Then extensive rewrites by Damon Lindelof ("Lost") and Drew Goddard ("The Cabin in the Woods") led to expensive reshoots that scrapped its action-adventure ending in favor of a suspenseful, lengthy new third act.

If the result isn’t an unqualified success, it’s at least more satisfying than most of what’s been dumped into multiplexes this summer.

When we meet Gerry Lane (Pitt), he’s making breakfast for his wife (Mireille Enos) and kids amid news reports of worldwide violence, martial law and a rabies outbreak in Taiwan.

Gerry used to do something or other for the U.N. Apparently he was quite good at it.

Also, apparently, he quit because it was ruining his marriage. So when a series of explosions and car crashes creates panic in the streets of Philadelphia — cue the inevitable "World War Z"-Springsteen mashup — Gerry’s better equipped to survive than most.

Amid the chaos, bystanders are being attacked. Twisting, convulsing and contorting as they’re infected, they start mauling others as though they were part of some insidious game of tag.

The entire process takes 12 seconds.

Philadelphia is laid to waste soon after, and the effect instantly feels more real than any of the large-scale devastation in "Man of Steel."

Thanks to Gerry’s U.N. connections, he and his family will be evacuated, assuming they can survive the night in Newark, N.J. — a dicey proposition under the best of circumstances.

After MacGyver-ing up some rudimentary weapons and defenses and enduring some near pants-soiling levels of terror, Gerry and the gang are choppered out of the nightmare to a command center onboard an aircraft carrier 200 miles out into the Atlantic.

He’s there for his expertise in international hot zones. Gerry’s the best there is. We know this because his old boss (Fana Mokoena) tells us. Also because, with his long hair, stubble, cargo pants and a scarf that must have set him back at least 500 bucks, Gerry looks like he just stepped off the pages of a catalog for J. Peterman’s Global Explorer line.

Before long, Gerry’s traversing the planet looking for patient zero, checking in with soldiers holed up in South Korea and seeking out survivors in Jerusalem, which somehow walled itself off just in the nick of time.

"World War Z’s" scope is enormous, and it doesn’t skimp on the spectacle. Its zombies are closer to the "28 Days Later" variety than their staggering, shuffling brethren on "The Walking Dead." They’re a frenetic, churning mass that descends on cities like locusts. It’s a good thing they’re not organized enough to form an Olympic team, or Usain Bolt wouldn’t stand a chance in 2016.

When Gerry and an Israeli soldier (a quietly powerful Daniella Kertesz) escape on a jumbo jet, well, let’s just say the only thing missing is a cameo from Samuel L. Jackson screaming about how he’s had it with these mother(expletive) zombies on this mother(expletive) plane.

Things get a little hokey at times, especially when it comes to the zombies’ attraction to sound. First, Gerry suffers through one of moviedom’s worst-timed phone calls. Then, during a stealth mission inside a Welsh laboratory overrun by zombies, he’s saddled with a scientist we’ll call Dr. Klutzy von Stumblebum who somehow manages to crash into everything in sight.

Still, those scenes, part of the massive rewrite, take on a "Jurassic Park," raptors-in-the-kitchen vibe and offer more old-school chills than anything in "The Purge."

Now that the undead are nearly as ubiquitous as Taylor Swift breakup songs, it’s understandable if you’re suffering from zombie fatigue.

"World War Z" follows in the decaying footsteps of this year’s zom-rom-com (zombie romantic comedy) "Warm Bodies" and BBC America’s recent "In the Flesh," in which zombies — err, sufferers of Partially Deceased Syndrome — are treated with pharmaceuticals and group therapy before being released back into society.

Like those projects, though, "World War Z" admirably breathes some new life into the genre.

So to speak.

Christopher Lawrence is the film critic for the Las Vegas (NV) Review-Journal. Contact him at clawrence@reviewjournal.com