This was a really well written book. It had a lot of plot twists, surprises, and some action all mixed together very well. The main character is named Cyn Hargrave, and she is not your normal teenager. She can take in souls into her own body, and they live there until they can get into the afterlife. These people are called echos. She has no control over the souls in her body, and they can take her over at any time. They cause Cyn to black out, and they can take over her body. The other main character is a demon named Avian. Heaven didn't want him, and hell shunned him. He is in charge of making sure that people don't get hurt from the monsters roaming the streets.