Former musician and gunslinger El Mariachi arrives at a small Mexican border town after being away for a long time. His past quickly catches up with him and he soon gets entangled with the local drug kingpin Bucho and his gang.
When Casey Connor, Herrington High School's newspaper photographer, witnesses the murder of a nurse and sees her alive again, he decides to investigate the bizarre happenings.
After an experimental bio-weapon is released, turning thousands into zombie-like creatures, it's up to a rag-tag group of survivors to stop the infected and those behind its release.