The Mistress' Gambit

Evelyn's husband, the Marquess of Ironhold, is away for long stretches and brings home a pregnant concubine; his mother rules the household and has spent years making the marchioness's life miserable. The woman in that role now is not the one who started it. A history student stayed up reading a novel, died of exhaustion, and woke inside the marchioness's body. She works out that she has to live to old age in this life, so she sets about making it bearable. She takes over the running of the mansion, fights her mother-in-law, wins over the children and the other concubines, and arranges a second marriage for the pregnant concubine so the woman is provided for. She sorts out the household's money and the children's prospects. In time she and her husband come to terms with each other.