19 books • 4 series
Book #1: Boundary
Book #2: Threshold
Book #3: Portal
Book #4: Castaway Planet
Book #5: Castaway Odyssey
Book #2: Demons of the Past
Book #1: The Mask of Ares
Book #2: The Spear of Athena
Book #2: Spheres Of Influence
Book #4: Shadows of Hyperion