London 1884. Electricity pioneer Simon Borthwick lights up Victorian London with a stunning illuminations display-then shoots himself in a hansom cab.

Plucky Fleet Street reporter Penny Green witnesses the inventor's death and suspects the clue to his suicide lies in a mysterious letter he left behind. But can she persuade Inspector James Blakely of Scotland Yard that a crime has been committed?

Borthwick isn't the only person who died that day and Penny soon encounters a shadowy world which the police can't get close to. When the intimidation begins, Penny starts to fear for her own safety. James does what he can to protect her, but is it enough?