When Augusta Peel finds a mysterious letter in a book she's repairing, her enquiries take her to Baker Street. But events turn sinister when she learns the address is linked to a missing person. Enlisting the help of Philip Fisher and his detective agency, Augusta attempts to solve a crime which has been hidden for ten years. Can the pair possibly match the skills of Baker Street's most famous resident, Sherlock Holmes? It's not long before the body count rises. And when someone discovers her true identity, Augusta's own secrets threaten to catch up with her.