A group of young adults headed to a secluded lake in upstate New York encounter an unsettling stranger and find themselves needing to spend the night at a neglected, isolated mansion. The question is whether they’ll survive the experience. "Deadly Manor” (1990) blends elements of 80s slasher films with the atmosphere of movies like "Hell Night" (1981). Released a decade after the original “Friday the 13th,” it's c…