Feisty teenage thief Maeko and her fellow pickpocket Chaff scrape out a meager existence in Victorian London's gritty streets. When a near-disastrous heist leads her to a mysterious clockwork cat and two dead bodies, she's thrust into a murder mystery that may cost her everything she holds dear.

Her only allies are Chaff, the cat, and Ash, the son of the accused murderer. What starts as a simple investigation reveals a conspiracy stretching across the entire city. With danger closing in around them, the only way any of them will get out of this alive is if they all work together.