It's been 5 years since the outbreak that wiped out 85% of the world's population, but the war between Re-Animates (Re-Ans) and Humans wages on. Most of the major cities are still uninhabitable. Within the few surviving cities, the Re-Ans have been segregated into "zones" and are policed by the R-Division of the QUASI S.W.A.T. Unit who hunt to re-kill the Re-Ans in the hope of quelling a second outbreak

http://www.youtube.com/watch?v=WQkmEOK5Dik