A young woman finds herself becoming obsessed with a violently disturbed man in this gruesome thriller inspired by actual events. Katie Armstrong (Keri Russell) is an American college student who is majoring in criminal psychology while studying abroad in Germany. Needing to explore a notorious murder case for a class project, Armstrong begins looking into the life and crimes of Oliver Hartwin (Thomas Kretschmann), who had been convicted of murder after killing and eating another man. Hartwin's crime was unusual in that he posted a message in an internet chat room asking for a male volunteer between the ages of 21 and 40 who would be willing to be murdered and cannibalized afterwards. While Hartwin did find a man willing to die and be eaten, this did not make matters safe or simple for the German cannibal. As Armstrong digs deeper into the horrible facts of Hartwin's crimes, she finds her reserve beginning to crack as she can no longer control her feelings about the killer. Also shown under the titles Grimm Love and Rohtenburg, Butterfly: A Grimm Love Story was inspired by the true story of Armin Meiwes, who was convicted of the 2001 death of a man he killed and partially ate who he met through a posting on the internet, in which he asked for a volunteer willing to be slaughtered.