Crusade in Jeans

16-year-old Dolf from Amstelveen signs up as a guinea pig: he will be flashed back to the Middle Ages by a matter transmitter to take a look there for one afternoon. At five o'clock that same afternoon, Dolf has to be at the agreed location again to be flashed back to the twentieth century.

But due to a miscalculation, he ends up in the year 1212 in a Children's Crusade and not at the knight's tournament he wanted to attend so much. And Dolf doesn't manage to be at the agreed location on time. Must Dolf now stay in 1212 forever?