The phrase is a common title in television and film, often exploring the harrowing discovery that someone close—a spouse, parent, or friend—is not who they appear to be. Depending on which series you are referring to, the Season 1, Episode 8 installment covers vastly different stories: 1. The Devil You Know (True Crime Series, 2010–)

Some listings for this episode also detail the story of Terri Lemoine , who lived with Gillis, a seemingly "loveable computer nerd". She was shocked when police revealed he was actually a serial killer who had murdered and mutilated eight women. 2. The Imperfects (Sci-Fi/Drama, 2022)

This show-within-a-show followed a journalist investigating a series of disappearances linked to a cult following of a popular TV show. Summary of Themes

The episode tells the story of Barbra, who believed she had married her soulmate—a successful Manhattan surgeon. However, her life unraveled upon discovering his dark secrets.

Across these various adaptations, the "Devil You Know" theme consistently revolves around: