54 books • 5 series
Book #2: Escape from the Island of Aquarius
Book #3: The Tombs of Anak
Book #4: Trapped at the Bottom of the Sea
Book #5: The Secret of the Desert Stone
Book #6: The Deadly Curse of Toco-Rey
Book #7: The Legend of Annie Murphy
Book #8: Mayday at Two Thousand Five Hundred
Book #1: Invitation
Book #2: The Assault
Book #3: Probing
Book #13: Piercing the Veil
Book #15: Fairy