Vaclav and Lena by Haley Tanner

Vaclav the Magnificent and the Lovely Lena have been planning their first performance at Coney Island for years.  The magician and his assistant, ten and nine years old respectively, have been best friends since an arranged play date five years earlier.  Although brought together by their shared Russian backgrounds and love of magic, their upbringings couldn't have been more different.  Every day after school Lena comes over to practice magic and eat dinner under Rasia's motherly eye.  She was also walked home and tucked in every night by Vaclav's mother. Unexpectedly, Lena starts to distance herself from Vaclav, is absent from school one day, and then goes missing altogether.  And all the magic in the world can't bring her back to Vaclav.  This is a touching novel of friendship, one in which you truly start to care for the characters and want the best for them.