The Outer Limits

Murder and its threat to the galaxy at large prompts a visit to Earth by Inspector Phobos (Barry Morse), a by-the-book Martian administrator. Staying with his "field man" Diemos (Carroll O'Connor), whose post is a seedy pawnshop, he is befuddled by the illogicality of this strange local custom that only seems to happen on Earth. Using a Martian device to examine a forthcoming murder, Phobos' compassion leads him to tamper with events -- and elicit from Mars the frantic alarm: "Fatal error!"