Rose Campion and the Stolen Secret by Lyn Gardner

Rose was left by her mother at the door of Campion's Palace of Variety and Wonders as a baby. It is her home, and she loves it, but she never stops wondering who she really is. When murder threatens to destroy the music hall, Rose will need all her performance skills to crack the crime and delve into a murky past of blackmail, subterfuge and abduction...