Fifteen-year-old Dolf uses a prototype time machine and gets stuck in the Middle Ages. Trying to find his way back to the twentieth century, he joins a children's crusade of almost ten thousand children on their way to the Holy Land. Dolf helps the children defy the terrible mountains, conquer disease and fight evil knights. Slowly, Dolf begins to realize that the real danger does not lurk behind the next mountaintop, but rather within the crusade itself.