What a wonderful, mystical piece of historical fiction. Four children - one in the early 1900s, and three in WWII era Europe and America - are connected by the power of a witch's spell and a magical harmonica. It was easy to love all the characters, and I particularly liked how each child highlighted the different struggles people were going through during WWII. Otto kicks things off by finding the magical harmonica and kicking off a chain reaction to save three sisters from a witch's curse. Decades later, there was Friedrich, a young boy living in Germany with a birthmark on his face, denoting him as one of the "unclean" eligible for a mandatory surgery under the twisted Nazi laws. Then there was Mike, an-eleven-year-old trying desperately to keep his brother Frankie safe and by his side as they live in a run-down orphanage in suburban Philadelphia. And finally Ivy, a Mexican-American who is forced to go to a separate, inferior school because of her race, even though she is brilliant. All three children find courage and perseverance through a seemingly magical harmonica, and their stories converge in the end, highlighting the healing power of music. 
 My only complaint is that I could have read a whole book about each individual character. It was hard to fall in love with each child and then have to jump to a new story (and all three ended in cliffhangers!). That's not really a complaint though, that's just me being selfish.