Complex sentence: Actors Charles McGraw and William Conrad play the hit men in the film, however the rest of the story, told in flashback, was created (rumored to be written by an uncredited John Huston) solely for the film.
Split into simpler sentences: Actors Charles McGraw and William Conrad play the hit men. The rest of the story, told in flashback, was created (by an uncredited John Huston) solely for the film.