Stars Brad Pitt, Mireille Enos, James Badge Dale, Daniella Kertesz, Matthew Fox, David Morse, Fana Mokoena. Written by Matthew Michael Carnahan, Drew Goddard, Damon Lindelof, and J. Michael Straczynski; adapted from the Max Brooks book. 115 minutes. Rated PG-13. Critic’s grade: B

Click, click, click go the choppers. Run, run, run, goes the movie star.

That’s about the extent of what happens in “World War Z,” the highly anticipated mega-budget ($250 million) adaptation of Max Brooks‘ clever “oral history” of a zombie apocalypse that very nearly wiped out the human race.

Rather than relate the dozens of individual stories of mayhem and heroism presented in the book, director Marc Forster (“Quantum of Solace,” “Finding Neverland,” “Monster’s Ball”) focuses on one man’s story. It’s all Brad Pitt, all the time, as Gerry Lane, a retired United Nations investigator — or something — is called back into action to travel the globe in search of a cure for what ails the freshly undead. In the film, the UN is positioned as the agency most capable of saving the planet; in real life, the organization is, like, the P.T.A.

Forster’s film, credited to four screenwriters, is kind of a combo horror flick, scientific-discovery mystery and international thriller, as Gerry’s travels take him from Philadelphia to South Korea to Jerusalem to Wales and finally to a refugee camp in Nova Scotia.

In this version, a zombie bite leads to a convulsing, eyes-bugging transformation into zombiedom in just a few minutes flat. As in Danny Boyle‘s “28 Days Later” and its sequel, but not in television’s “The Walking Dead” or in the George A. Romero films, these flesh eaters are fast, scary fast.

Both of those characteristics are fully displayed near the start of “World War Z,” as Gerry, his wife (Mireille Enos) and their two girls drive through Philadelphia, off to run errands after a warm and fuzzy prelude at a comfortable home in a leafy suburb. First, they’re ensnared in a traffic jam, then motorcyle cops and others start fleeing from some distant trouble spot; the flow of human traffic and suggestions of a terrible urban disaster will remind some of the streets of Manhattan, during the 9/11 terror attacks.

This time, though, the enemy is us, or, rather, a version of us as infected by a disease that turns humans into teeming masses of nasty looking people looking to satisfy their chomping urges as soon and as often as possible. The snippets of news clips during the opening credits hint at what’s to come, with the animal kingdom askew, CO2 emissions rising fast, and routine nature images — ants swarming, birds flocking — coming off as ominous. “Mother nature is a serial killer,” one scientist type says later.

A quick flight, a melee at a Newark, N.J., grocery store and a helicopter rescue later, and Gerry and Co. are on an aircraft carrier, where mom, the kids and a tag-along child will reside while dad is on his mission to save the world.

Technically, “World War Z” isn’t really frightening, and it’s hardly gory at all — far more blood and guts are spilled in “The Walking Dead” and in the terrific new BBC zombie series “In the Flesh.”

And, while there is one scene of apocalyptic, zombie-caused destruction in Jerusalem — historically, end-of-days scenarios play out in the Middle East —  Forster’s film doesn’t dwell on an endless series of scenes of large-scale devastation and stuff blowing up. That’s a positive, I think.

Instead, he downsizes and, in some respects, personalizes, the horror, with several sequences that are darn suspenseful, including that early rooftop escape, a mad dash from a military base to a cargo plane, an unexpected zombie attack on a moving airliner, and, in particular, a surprise getaway inside a World Health Organization lab teeming with the nasties.

Does Gerry discover a long-lasting solution to the zombie problem? No spoilers here.

But, if “World War Z” somehow manages to recoup its sky-high budget, real answers may reside in follow-up films: “This isn’t the end, not even close,” we hear in a voiceover. “Our war has just begun.”