There is no room for Clare the Adventurer in Hameln, a German town with hundreds of years of history, much of which has been kept secret from her. When a shocking murder leads to a plague of rats ruining her hometown's once-a-decade Obolen festival, Clare realizes there's more at stake than just losing her younger brother, the last in her family, to a distant apprenticeship.

Thirteen-year-old Sophie is nobility, but that doesn't mean she has to stay on the sidelines waiting for everyone else to clean up the mess of rats running amok in Hameln. She's jumping in, uncovering potential suspects, and getting in Clare's way during every step of an investigation leading her deeper into her family's darkest secrets.

Lukas, a wandering minstrel with a magic flute, might be the answer to all of their problems-if he didn't annoy Clare so much. He can't understand why she won't tell him what's really in her heart and she doesn't know why he's truly in Hameln. Every day, the increasing swarm of rats prevents Lukas from wooing Clare. When he rids Hameln of its rats, a whole host of deadly truths emerge, putting him and his fellow teens in grave danger.