Eliza is hired by Scotland Yard to find a missing Lord accused of murdering his maid, but when the new Detective Inspector arrives, he removes Eliza from the case. DI Blake has his own rule about not using private detectives and Eliza now has a fight on her hands to convince the new boss that she is an invaluable resource.

The all-powerful Guild of Private Detectives take an instant dislike to the new Inspector Blake because of his ban on the use of Private Detectives at Scotland Yard. But when the Chairman of the Guild turns up dead, Blake finds himself working alongside Eliza whether he likes it or not. Meanwhile, Ivy takes on a new opportunity, but what will the consequences be for her engagement to Mr. Potts?

With a notorious serial killer on the loose Eliza is caught in the middle of a clash between Fleet Street and Scotland Yard.