Two and a half decades before “The Walking Dead” made zombies mainstream on cable television, 19-year-old writer/director J.R. Bookwalter (“Ozone,” “Witchouse 2: Blood Coven”) embarked on “The Dead Next Door,” an ambitious horror feature pitting an elite team of Zombie Squad soldiers against hoards of the undead and the secretive religious cult hell-bent on protecting them. Available in HD for the first time, this 16:9 widescreen presentation was painstakingly created from a 2K restoration using the original Super-8mm film elements.