Finding English subtitles for Devil in the Flesh depends on which version of the film you are looking for, as there are several adaptations of the Raymond Radiguet novel.
OpenSubtitles : One of the largest global databases for multi-language subtitles. Devil in the Flesh subtitles English
: Many apps like Plex or Roku allow you to toggle "Captions" or "Subtitles" in the playback settings menu while the movie is running. Finding English subtitles for Devil in the Flesh