The Strangers (2008)

A young couple is traumatized and killed in their isolated house. The writers were inspired by the real-life murders committed by Charles Manson. Writer-director Bryan Bertino also said that the film was inspired by something that happened to him in his childhood. People knocked on his door when he was a child while his parents were away and they asked for someone who didn't live there. Later he found out that they were responsible for a series of break-ins and robberies.