Nati & Tzviki

Someone is vandalizing Mr. Krovitz's Judaica store, causing him and his family, who have just come from Russia, a lot of damage and frustration.  Who's doing it and why?

Best friends Nati and Tzviki want to help figure out the identity of the vandal.  They watch the action surrounding the store from afar, only to discover that Sasha, the owner's son, doesn't want their help or their friendship.  Why not?

Who is the suspicious Russian fellow that spends hours outside the store each day?  Is he a spy, or maybe a terrorist?  And what is an old photo of Uncle Naftali doing on the principal's desk?