Ryan Nelson

When a new professor's methods leave Hogwarts unprepared to fight the rising tide of evil, Harry teaches students how to defend against the dark arts.

Dolf a 15 year old boy is sent back in time by a timemachine. Accidentally he is sent back to the Middle Ages. He is rescued by children who are part of a childrens' crusade, on their way to rescue Jeruzalem. During the trip Dolf finds out the danger is not coming from outside the crusade, but from within.