When you're 12 years old, every day's a new discovery. But nothing could prepare David for the adventure which lay ahead. For a start, imagine waking up one day to discover you'd lost eight years of your life! Everything - his mum, his dad, even his dog - changed. Everything, except him. And that's not the only thing that's weird. Why is David's brain sending out strange signals even he can't explain? And why do a group of top-secret government scientists want to lock him up and study him as a national security risk? The truth is even stranger. Because even though David's just a kid, his mind's the key to the most amazing discovery on earth, a visitor from another part of the universe. It's time for a risky trip through time and space, with David at the controls - because he's the Navigator.