The undead as represented in the upcoming film "World War Z" appear to be of the fast, angry variety. As any fan of the genre will tell you, zombies can sometimes come in different flavors — from the slow, meandering versions found in the original "Night of the Living Dead" to the sprinting, rabid mobs displayed in "28 Days Later."

"World War Z's" Director Marc Forster, adapting Max Brooks best-selling novel of the same name, appears to be embracing the latter — with this latest spy video from the recently completed Glasgow shoot giving us an example. In the clip, a man is pulled from his car, bitten by a zombie, and then quickly transformed (with some clever physical acting) into a vicious monster. 

In a recent interview with SlashFilm, Brooks said he was impressed with the Glasgow set — and the how his vision of the zombie hoards was being brought to life. 

"They look very much like what my impression would be of new zombies who had not really begun to rot, kind of like phase one zombies," he said. "They have a zombie school, where they are teaching extras how to act like zombies, and from talking to people on set they have really put a lot of research into everything."

Check out the clip below. "World War Z" is set to be released Dec. 21, 2012.

Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

'World War Z' set clip shows zombie infection
Spy video reveals just how creepy director Mark Forster will make his undead army.