Maisie Dobbs book by Jacqueline Winspear

Maisie Dobbs, Psychologist and Investigator, began her working life at the age of thirteen as a servant in a Belgravia mansion, only to be discovered reading in the library by her employer, Lady Rowan Compton. Fearing dismissal, Maisie is shocked when she discovers that her thirst for education is to be supported by Lady Rowan and a family friend, Dr. Maurice Blanche. But The Great War intervenes in Maisie’s plans, and soon after commencement of her studies at Girton College, Cambridge, Maisie enlists for nursing service overseas.
Years later, in 1929, having apprenticed to the renowned Maurice Blanche, a man revered for his work with Scotland Yard, Maisie sets up her own business. Her first assignment, a seemingly tedious inquiry involving a case of suspected infidelity, takes her not only on the trail of a killer, but back to the war she had tried so hard to forget.