The story is the third in a trilogy written by Phil Nutman and Daniel Farrands (the later wrote Halloween 5: The Revenge of Michael Myers). Though really this one shot can be viewed as beast in itself. What the writers behind this did was combine both H20 and movies 4-6 into one universe.
The plot to this particular one-shot is about the young children who Laurie babysitted from the original movies twenty-three years later, Tommy Doyle and Lindsay Wallace. Tommy's in the nuthouse run that's still run by Wynn (the occult obbessed doc who tried made Mikey what he is as revealed in Halloween 6). After an attempt on his life via Wynn and corrupt guard, Tommy breaks out, though en route out see's Micheal watching him.
Lindsay returns to Haddonfield very much haunted of those events twenty-three years ago. It's then she hears a newscast:
Not soon after Lindsay recieves two phone calls both of which have nobody talking on the other end. Yep.. Mikey still using the old call and not answer back thing like in the original. Not soon after threatening to use caller id and find out who this pranking punk is Tommy show's up.
They talk about Loomis's journal and an entry he has with a woman who used to work at Smith's Grove. Not soon after Tommy and Lindsay hear something upstairs. They go and take a peak finding:
Lindsay as Laurie before her tries pleading to people to help her. Some people who whiz by her in a car pay no mention and almost run her over. Several houses whose doors she knocks on give no answer at all. It isn't soon before Lindsay finds herself right in front of the Myers' residence. Knowing Mikey hasn't given up the hunt, she decides to make a stand.
Tommy and Laurie take a tumble out the window and fall to the ground. Of course given the fact he now has a glass shard in this throat, Tommy is so dead. Laurie on the other hand well.. still alive and giving that emotionless look upon her face.
We then cut to the next day with Laurie now committted to Smith's Grove with a Doctor and Lindsay watching over her. The Doctor theorizes Laurie went over the edge after she killed Michael. That even taking his head wasn't enough for her. That she couldn't survive without the idea of Michael. So in essence, she "became him".
Interestingly, this story was what Farrands had in mind when the prodocers for the horror series asked him for what Halloween 8 was to be (which turned out to be Halloween Resurrection). He took in the fact Jamie Lee Curtis was contracted only for a cameo for the eighth film and really wanted to make the most of it. He also wanted to go into Mikey's time in Smith's Grove besides the stuff above with Tommy and Lindsay being the protragnists. Unfortnately, his ideas got rejected and the people behind the franchise decided to go with Resurrection.