The single great ass-kick of last summer — and the only film of the year to leave you that true action-movie smeared-on-the-inside feeling of having lived through something. Four survivors of an epidemic flee an England overrun by howling, scampering zombies. The story poses essential questions of what “survival” actually means (and then answers them: It means not being devoured by fucking crazed zombies). Disc extras are mostly serviceable: The commentary track fills its cultural function of being a repository for transient factoids (“Chimps can only act to age seven”) and filmmaking-on-the-fly tips (“Paper drifting through a shot is always a good, cheap way of suggesting an apocalypse”). The supposedly tougher endings boil down to whether the hero lives, and a crap featurette consists of qualified medical doctors being encouraged to agree, “Yes, this could legitimately happen.” So switch it all off and just watch what happens to be the best post-9/11 movie yet.