As London's only female detective, Eliza is struggling to get work. Desperate for money, she takes a seemingly impossible case; proving the innocence of a man found at a murder scene with a bloodied knife in his hand who has pleaded guilty.

The Duke hires Eliza to spy on suffragettes. Going beyond her instructions, she gets involved in Britain’s biggest plot since Guy Fawkes.

Searching for the secret to her father’s fate, Eliza goes to an abandoned prison. Eliza and the Duke stumble on a criminal enterprise.