A Dangerous Secret — Ian Bone

When Hamish wrote an embarrassing essay about how movies meant more to him than real life, he thought only a teacher would read it. But he wasn't counting on nosy classmates, a smarmy bursar, and a mysterious note in his locker saying, "You have been chosen to fight evil. This is not a prank!"

The note-writer gives Hamish a Vidz and tells him to watch it alone. Hamish soon learns that it's no joke. The Vidz throws him into A Dangerous Secret, a movie starring Sir Hamish, the people's champion. Hamish doesn't mind sword and sorcery movies -- but not when he's the knight, he's forgotten where he left his sword, an angry mob is chasing him and he's lost his memory after being tortured in the king's dungeons.

He can yell "Cut!" to go back to the real world, but the evil Lord Dudley's power is growing in the Vidz and strange things are happening at Capra Video High School -- and Hamish is the only person who can do something about it.