Today screenwriters pitch their visions to producers, but in old Hollywood they were simply assigned. In the beginning years of the movie industry the studios had writers, directors, producers and actors on contract and the key decision-makers - giants like Louis B Mayer, Irving Thalberg, Darryl Zanuck - would mix and match these components as they saw fit. If you were a screenwriter at Warner Bros you would come in one day and find out you were assigned to a Jimmy Cagney movie, then get assigned a to a Rin Tin Tin movie. That's what happened to Herman Mankiewicz.
Mankiewicz was one of the most important writers in early Hollywood; he's best known for his screenplay to Citizen Kane, but Mankiewicz had been working in the industry since the silent era. Mankiewicz's sly, witty and satirical style became almost totally synonymous with American movies in the 30s. Fast-talking wisecracking characters were a Mankiewicz trademark, and everyboy from Billy Wilder to Aaron Sorkin is descended from him. A New Yorker, Mankiewicz helped pave the way for very smart East Coast writers to come out to Hollywood. He famously sent this telegram to Ben Hecht not long after finding success in the movies:
"Millions are to be grabbed out here and your only competition is idiots. Don't let this get around."
Genius as he was, Mankiewicz was still part of the studio system. A hard drinker and serious gambler, Mankiewicz's vices often caused headaches for the studio bosses. Sometimes those bosses fought back by giving him shit assignments, and legend has it that's how he ended up with a Rin Tin Tin movie on his plate.
Rin Tin Tin is largely forgotten today, but the dog was a major star in the first half of the 20th century. A shellshocked pup discovered by American GIs in France during WWI, Rinty (as he was originally named) learned tricks and could jump amazing heights. His stunts got him into the movie business, and his first starring feature, Where the North Begins, was such a huge hit that it took small studio Warner Bros and made it a major player. Studio head Jack Warner called Rin Tin Tin 'The Mortgage Lifter' and signed the dog to an incredible $1,000 per week contract. The dog was the biggest star at the studio.
But he was still a dog. And Mankiewicz, who prided himself as a writer, was forced to come up with the hacky formula story for his next film. So he hatched a plan.
Some time later Mankiewicz turned in his script. Rin Tin Tin was a police dog in this story, but instead of a courageous defender of the weak, he was a coward. And, in a third act twist no one saw coming, Rinty reversed his usual behavior and carried a baby into a burning building, where presumably both died.
Mankiewicz was removed from the film and never again assigned a Rin Tin Tin movie. At least that's how the story goes; it's possibly apocryphal, and it's credited to the great Nunnally Johnson, who won an Oscar for The Grapes of Wrath. He told that tale to Groucho Marx, and Pauline Kael immortalized it in her longform piece Raising Kane, a piece that defends Mankiewicz's role in writing that fillm (Mankiewicz always claimed he wrote the whole film, but he shared co-writing credit with director Orson Welles). Is the story true? Who cares, it's good.