Birdie is an orphan in London (circa 18070s) who is working for Alfred the Bogler. Together they are successful at capturing bogles/monsters and they live a comfortable life together. The only thing is they never know when their next case will pop up so their income isn't steady. The talent that Birdie has to offer is that she is a very good singer. Her melodic voice (done well on the audio which I listened to) hypnotizes the monster(s) into submission. Some other people in England find out about their partnership and the work that they do. Some of those people are good and some are evil. Suddenly, Birdie has been kidnapped. By whom? For what purpose? What happens next? You will have to read the book! I loved Birdie's strength in this book.