Crusade in Jeans (2006)

"Crusade in Jeans" is a 2006 Adventure movie directed by Peter Wooldridge and starring by Johnny Flynn, Stephanie Leonidas. 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.