The Stepfather tells the story of John Blake (played by Terry O'Quinn), a man murdering his way from one family to the next, changing his identity each time before moving on; it is loosely based on the true story of John List. The film starts with a fantastic and creepy transformation scene, in which O'Quinn prepares his next persona, then calmly walks past his murdered family and out the door, in search of his next target. It's not long before he settles in with a new family, but quickly finds them lacking as well.
The story unfolds at a natural pace and the characters are very well constructed. The killing that does happen is sudden and very brief, making these scenes all the more effective. In some ways, The Stepfather is more a thriller than traditional horror - it has also been pointed out that the plot is similar to Hitchcock's Shadow of a Doubt.
Terry O'Quinn is amazing in this film. He is subtly creepy at times (particularly in scenes with his step-daughter), but when he finally loses control it is truly scary. The height of his performance is during the "who am I here?" scene that occurs towards the end. Prior to The Stepfather, O'Quinn appeared in the adaptation of Steven King's Silver Bullet, and in the years that followed, he starred in Pin (1985) and Stepfather II (1989), before moving onto the roles that he is best known for, in The X-Files, Millennium, and LOST. Jill Schoelen who plays his step-daughter would later star in Popcorn (1991).