A group of young adults head out to a secluded lake in rural Southern California for a summer outing, but they encounter something disturbing. The only ones who seem willing to accept their account are two elderly local men—played by Jack Palance and Martin Landau—who appear to be somewhat unstable. Christopher S. Nelson and Tarah Nutter portray the central characters. "Without Warning," released in 1980, is a little-known horror film that clearly had an impact on “Predator” (1987). While "Predator" may be considered the more polished movie overall, I personally find myself drawn to this smaller, less extravagant production. It manages to create some genuinely unsettling moments and a pervasive sense of unease. In terms of its special effects concepts, it draws inspiration from Star Trek episodes like “Operation - Annihilate” (1967) and "The Corbomite Maneuver" (1966), combining that with the setting reminiscent of “Tourist Trap” (1979) and elements seen in “Squirm” (1976). The presence of Palance and Landau as eccentric characters also foreshadows the later film “Alone in the Dark” (1982). While Tarah Nutter does a decent job portraying Sandy, the female lead, Lynn Theel’s performance as Beth is particularly memorable. Christopher S. Nelson is easy to root for as one of the male leads; he seemed destined for greater success, but his career remained largely confined to television and smaller film roles. My rating might seem a bit generous for what is essentially a “B” grade horror movie—and it does run about 12 to 15 minutes too long—but it succeeds in delivering the expected elements effectively, including a noteworthy piano-driven soundtrack. The film’s runtime is 1 hour and 29 minutes, and filming took place primarily at Paramount Ranch, Agoura, California (the main location), along with the nearby Agoura Valley Inn (for a bar scene) and Malibu Creek State Park (where the lake scenes were shot). GRADE: B-/B

Source on TMDB