"The Misfits" would be Marilyn Monroe's final film. The 1961 modern-day psychological Western was ravaged by her physical troubles on-set and the collapse of Monroe's marriage to the movie's screenwriter, Arthur Miller. And the emotional devastation of the movie's plot was reflected by what went on during its making, as Miller, director John Huston, and co-star Eli Wallach hatched a plan to rewrite the movie. The resulting adjustments would have had major consequences, changing the plot to raise Wallach's heroic profile and diminish Monroe's.

Wallach was an old friend of Monroe's from the Actors Studio in New York. According to Les Harding's "They Knew Marilyn Monroe," he credited the actress with getting him cast in "The Misfits," but by the time the movie was being made, something in their friendship had shifted. Beyond the rewrites, he used the movie to execute a couple of practical jokes on her,...