Inspired by the remarkable life of Dorothy Peto, the Metropolitan Police's first female superintendent.

Even in war, your enemies can linger too close to home...

While war and revolution continue to ravage Europe, Dorothy Peto embraces her new role at Scotland Yard as she and several detectives investigate a series of jewel thefts. Then Dorothy is tasked with assisting the inscrutable Inspector Derwent and the charming Colonel Lamarchant to find a missing French aristocrat. Their enquiries take them to a country house in Yorkshire, that's been converted to a hospital for wounded soldiers and was the last place the Frenchman visited. However, the more questions they ask, the more questions they have.

When the body of a man suspected of being the marquis is discovered, the investigative team returns to London, but the dead man is a stranger. Dorothy speculates that the death, the jewel thefts and the missing Frenchman may be connected. She finds herself tangled in a web of conscientious objectors, Irish republicans and communist agitators, and not everyone is who they appear to be.