The series is known for being dreamlike and incoherent, but it's always been extra weird to recast Mike, then unrecast him after. It supports that whole multiversal plot in part 5. In some universe, Brad Pitt probably did play Mike. In some other universe, Bruce Campbell did star in that one sequel idea after all. At least we'll always have Bubba Ho-Tep in our universe.
Mike is released from psychiatry, when he agrees with the doctors that the terrible happenings in his past were just in his imagination. But once he's free, he contacts Redge and they team up to hunt down and eliminate the "Tall Man", who plunders the graveyards and steals the corpses with help of his terrible dwarfs. A beautiful strange girl starts to appear in Mike's dreams. He assumes she's in danger and needs their help - will they find her before the Tall Man can do her any harm?