The studio has also released the following brief synopsis:
“The story revolves around United Nations employee Gerry Lane (Brad Pitt), who traverses the world in a race against time to stop the Zombie pandemic that is toppling armies and governments and threatening to decimate humanity itself. Enos plays Gerry’s wife Karen Lane; Kertesz is his comrade in arms, Segen.”
World War Z, rated PG-13, stars Brad Pitt, Mireille Enos, Anthony Mackie, James Badge Dale, Bryan Cranston, and is directed by Marc Forster (Finding Neverland, Quantum Of Solace).
I've never read the novel, but according to The Collider it is a bit different than what the studio's synopsis reads.
"The plot of the book takes place after a zombie apocalypse and has a researcher for the UN going around the world to determine the cause."