If it wasn't for one Stephen King story, Mike Flanagan would not have been a horror director today and would also have never directed one film. While Stephen King is often referred to as the "King of horror," and rightfully so, Mike Flanagan, too, has established himself as a horror auteur by consistently delivering acclaimed television shows and movies. However, long before Flanagan came to be known as one of the most talented figures in the horror genre, he was struggling to find his feet as a filmmaker.

https://screenrant.com/mike-flanagan-stephen-king-story-inspired-1408-oculus/