Immediately after his arrival in Milan, where he intends to spend a study visit, SEBASTIAN, a Jesuit novice from Munich, falls victim to a pair of under-age tricksters. SEBASTIAN tracks down the young thieves and is horrified to discover a criminal organisation that kidnaps children from all over Europe and subsequently trains them to become thieves and robbers. The two children who have robbed SEBASTIAN, 12-year-old LAURA and her 14-year-old brother LUIS, are also members of a children's gang. SEBASTIAN leaves no stone unturned to get in touch with them and to save them and their friend THIERRY-BIBI from disaster. He soon discovers the leaders of the gang to be unscrupu-lous criminals who will stop at no act of violence. For no sooner do they realize that SEBASTIAN is on their trail than they try to kill him. But the young monk does not give up easily. Together with GIULIANA, the niece of a Milanese Monsignore, he imperturbably traces the children.