A film based on the popular Travis McGee series of detective novels. Since I have never read any of these books and am barely aware of the character Travis McGee this was all news to me.
Darker Than Amber is supposedly considered a cult film. But you would have to read a lot into this film to figure out where the cult status comes from. Maybe the brutal fight scenes or the chief psychotic (what else) villain played by veteran character actor William Smith are supposed to give the film its cult status but I think that would be pushing it.
Darker Than Amber was directed by Robert Clouse whose claim to fame is Enter the Dragon. Clouse isn't particularly adept at staging action scenes or actually any scenes for that matter. The film kind of plods along from one story point to another, McGee falls in love, McGee solves a murder, McGee has a fight with a real touch guy, etc.
Veteran actor Rod Taylor is Travis McGee but he basically plays Rod Taylor. Suzy Kendall who had been in some Italian Giallo films is the love interest.