What is the plot of Echo by Pam Munozryan?

The narrative relates the story of three princesses who give a harmonica to a boy named Otto with instructions to pass it along at the right time. The harmonica travels to a boy named Friedrich, another named Mike, and to a girl named Ivy, before landing in the hands of a young soldier named Kenny. When the harmonica saves Kenny's life, the spell on the three princesses is broken while Friedrich, Mike, and Ivy each realize their musical dreams, bound together by the magic of the harmonica.