Tired and worn from years of chasing hardened criminals, Detective Inspector Samuel Harris wonders why he is still in the police force. Then, in 1923, his niece, Lettie Jenkins signs up to join the police just as women are allowed among the ranks. Sam knows she's walking into a lion's den. Is she tough enough for the streets of London? He soon finds out when she finds herself face-to-face with her first murder victim. Lettie is full of energy, enthusiasm, and a passion for the job that Sam has long since lost. Will he stand by and let her take on all the force and London have to throw at her? Is she a tough enough woman to handle being a policewoman in a man's world?