Rudolf Hefting of Amsterdam thought he was engaged in an experiment that would take him back to the Middle Ages to a tournament of knights. But by a miscalculation of the computer, he arrives in the Rhineland at the exact time that the Children's Crusade is passing through. A stranded traveler in time, Rudolf joins the immense children's army -- almost 10,000 strong. With Rudolf, the reader struggles to understand how it was possible that children between the ages of 6 and 15 thought they could travel across Europe, then cross the sea to drive away the Saracens from the Holy Land. They had no weapons, transportation, or money; they experienced hunger, epidemics, and death. The dreadful conditions he encounters compel him to use his 20th-century knowledge to try to create order out of chaos. In spite of himself, he becomes a leader and organizer. And along the way he also experiences loyal friendships, courage, and devotion to God.