The Secret of the Mezuzah

Imagined dangers become very real as a quest for intrigue leads to a disturbing discovery. . . . Fifteen-year-old Constantine Rea is bored with life in Vienna Austria, since it seems nothing that exciting ever happens there. But then an acquaintance tells Con that the old city has always been a center of international espionage. In fact, one out of ten adults living in Vienna is a spy! Con knows at least ten adults . . . but could one be a spy? Con and his best friend, Hannah, devise a plan to unmask the identity of the spy in their midst, but their plan is put on hold when Con and his mother make a trip to visit their old landlord, Herr Donner. While there, Con receives a curious gold object called a mezuzah, a symbol of Jewish faith. Then Donner has a chance to rethink the gift, and he angrily demands its return-but Con refuses. What is so important about the mezuzah, and why did Donner have it in the first place?