Stephen King's 1989 novel Secret Window, Secret Garden have very similar plots, and that's not by accident. The Dark Half, as so many of King's stories do, focuses on a writer. Thad Beaumont pens award-winning literature, while his alter ego George Stark writes best-sellers in the mystery and thriller genres. That set up is going fine for Thad, until George somehow emerges into the real world as his own separate entity, one that has no problem murdering people who get in his way.
Secret Window, Secret Garden - part of the Four Past Midnight collection - focuses on a novelist living in Maine named Mort Rainey. One day, Mort is confronted by an unstable man named John Shooter, who accuses him of stealing his titular story, and sure enough, a story Mort had written called Sowing Season turned out to be virtually identical to the manuscript presented to Mort by John. However, Mort has no recollection of stealing anyone's story, and things between the two men get volatile quickly.
As the final twist of Secret Window, Secret Garden reveals, John Shooter was actually just a split personality conjured up by Mort's brain due to his guilt over actually stealing a story early on in his career. The similarities in plot to The Dark Half are quite obvious, but King very much designed the story that way.
Stephen King: Why The Dark Half & Secret Window Have Similar Plots
As Misery was in part designed to examine the powerful hold fiction can exert over its readers. Conversely, one of the main ideas behind The Dark Half was to take a look at the similarly powerful hold fiction can have over the person writing it. While in the process of writing The Dark Half, King had an idea how he could explore the latter concept again, but this time through the lens of how he believes writing to be a secretive act, with the process behind the creation of a story only ever fully known to the writer.
Out of that thought came Secret Window, Secret Garden, which King envisioned as taking elements from The Dark Half but realizing them in a new way. Whether he succeeded as far as the newness factor is up for fan debate, but both stories certainly have their pluses, and both went on be adapted into movies. Thad Beaumont and George Stark were played by Timothy Hutton, while Mort Rainey and John Shooter were played by Johnny Depp and John Turturro, respectively. In a fun touch, Hutton actually plays a ing role in Secret Window, although it's unclear if that was a purposeful nod.
