World War Z shuffles its way through a globe overrun with the undead.

Sequels and James Bond films can begin with large-scale action sequences because we know who the characters are and can easily grasp why they’re in a perilous situation. But if we don’t know the characters and the action lacks energy, as is the case with World War Z, it’s especially grating because you’re bored and have no idea why anything is happening.

There are zombies, we do know that. They’re fast, strong and aggressive, and with people turning roughly 12 seconds after being bit, the zombies are multiplying at an alarming rate. What’s causing this is never explained, which is annoying, but not nearly as frustrating as seeing Gerry Lane (Brad Pitt), his wife Karen (Mireille Enos) and their two daughters (Sterling Jarins and Abigail Hargrove) get special attention from the government for (at this point) no discernible reason.

It’s not until later we learn Gerry is a former U.N. investigator with experience in war-torn areas. With a pandemic in full swing, Gerry traverses the globe looking for the person who started the zombie-causing virus, a.k.a. “patient zero,” as it’s believed the origin of the disease can also provide the antidote. If Gerry doesn’t help, his family will be kicked off their safe haven cargo ship and placed in harm’s way.

Soon Gerry finds himself in South Korea, Jerusalem and Cardiff, Wales, slowly but surely figuring out how to combat the omnipresent virus. Between various misleads and dead ends are high-octane action scenes, only one of which, on a plane headed to Wales, is notably impressive (but not nearly as good as the plane crash in Liam Neeson’s The Grey).

The visual effects are adequate, highlighted by the aforementioned crash and the way zombies swarm like ants to climb a wall in Jerusalem, but overall the movie isn’t visually dynamic. Thankfully, though, director Marc Forster (Quantum of Solace) gives us a PG-13 rating, which spares us excess violence and gore.

The movie is based on the best-selling book of the same name by Max Brooks, but fans of the novel will only see scant elements of it here. Brad Pitt’s production company, Plan B, won the rights to the novel and with The Walking Dead and other undead-related content all the rage right now, it’s easy to see why he thought this could be a profitable big-ticket franchise. But what makes The Walking Dead so successful – the central question of, “What becomes of humanity when all hope for mankind is lost?” – is completely absent here, shoved aside for the sake of post-apocalyptic action that doesn’t want the audience to think for a second about what’s going on.

Unfortunately, World War Z is flat from the start. It sort of ambles its way along, with excitement popping up here and there, always ready to feast on an action scene with reckless abandon because nothing else of interest is happening. You know, kind of like a zombie.

WORLD WAR Z (2) •Directed by Marc Forster • Starring Brad Pitt, Mireille Enos, James Badge Dale • Rated PG-13. 116 min. • At Maya Cinemas, Lighthouse Cinemas, Century Cinemas Del Monte, Cannery Row XD and Northridge Cinemas.