What makes the Final Destination movies such irresistible shlock? In each of them a group of teens narrowly avoids disaster (a plane explosion in the first, an expressway crash in the second, now a roller-coaster crack-up), but then they die one by one in freak accidents, victims of an irate grim reaper. The death scenes in this third installment brave new frontiers in splatter slapstick, each resulting from a ludicrous chain reaction of chance events; meanwhile the heroine (Mary Elizabeth Winstead), who foresaw the roller-coaster crash and shot a series of prophetic photos, races around trying to second-guess death’s design. If you’ve seen any of these, you know that the hero is always killed for her trouble, a final stroke of mordant wit. James Wong directed. R, 92 min.