In interviews, Bertino stated he was "very impressed" with some of the theories circulating on the Internet about the "true events" the movie is allegedly based on, but said that his main inspiration was the true crime book "Helter Skelter", which is about the Manson Family murders; some journalists speculated that the film was also inspired by the unsolved Keddie Cabin Murders of 1981 that occurred in a small vacation community in California's Sierra Nevada. The film's premise has been compared by some film critics to the French horror film "Them", released two years earlier, which also features a couple terrorized by strangers in their remote home.