HARRY POTTER / THE MATRIX FIC

Harry was sitting alone in his room thinking about his friends, Ron and Hermione from Hogwarts. He had the house to himself as his aunt, uncle and cousin had gone out for the day and left Harry behind (after a stern warning from uncle Vernon about 'funny business') so that he wouldn't ruin their day.
Suddenly a tapping at the window broke into his thoughts. It was an owl, so he opened the window to let it in. The owl was carrying a piece of parchment with two lines of typed writing on it.

The Matrix has you, Harry.
Follow the owl.

This seemed very strange, even to Harry who was a wizard. Questions whizzed through his head. Who sent this? Where would the owl take him? And more importantly, what was the Matrix?
The owl perched on the window sill blinking at him expectantly. Without really knowing what he was doing or why he was doing it, he grabbed his wand and ran down the stairs and out the door so he could follow the owl who had flown back out of the window as soon as it looked like Harry might be doing something. Harry couldn't help feeling that what he was doing was really stupid. What would uncle Vernon and aunt Petunia do when they discovered he was missing? Would they try and find him? No, they'd probably join his cousin Dudley and celebrate, he told himself. Why was he doing this? But he knew the answer to that. He wanted the answer to the burning question going round in his head - What is the Matrix?