R K Hinrichsen: 4 books

THE DARK ENEMY NEVER RESTS, BUT NEITHER DO THE HEROES OF THE HIGHEST ORDER. Dan learns he's even more powerful than he thought when he and Page search the catacombs in Italy, escape the enemy in the streets of India, and follow in the footsteps of Mother Teresa to rescue their grandfather from the Prison of the Shadows.

THE DARK ENEMY NEVER RESTS. BUT NEITHER DO THE HEROES OF THE HIGHEST ORDER! A magical playground whisks Dan and Page into the Hidden Kingdom where a skinny giant quickly registers them for hero training camp. There, they learn they must gain skills and earn a powerful treasure of peace by travelling back in time and walking in the footsteps of a real pioneer hero.

THE DARK ENEMY NEVER RESTS, BUT NEITHER DO THE HEROES OF THE HIGHEST ORDER! Book 1: The dark enemy never rests. But neither do the Heroes of the Highest Order. So when a magical playground whisks Dan and Page into the Hidden Kingdom, a skinny giant quickly registers them for hero training camp....

THE DARK ENEMY NEVER RESTS, BUT NEITHER DO THE HEROES OF THE HIGHEST ORDER. Tadeusz Pankiewicz, a real-life hero, helps Dan and Page rescue two children from the Nazis in World War II Poland.