Gambling Lion, Antoinette George, Brangwyn Press, 2021
Set in Western Europe of the Napoleonic Era, this novel is about Nicholas de Bresancourt, a French duke whose lands were confiscated by the French authorities. Working for the British (in their war against France) as a courier and spy, he spends a few days in London, waiting for his next assignment. He catches up with his adoptive family, and visits Mayfair's hottest gaming club, Le Lion D'Or.
Run by a masked woman who calls herself La Lionesse, she invites him upstairs, where they can be alone, all night. She turns up the seduction "dial" as high as it will go. This goes on for several nights; Nicky would be very angry if he saw her face.
Meantime, he is given a new and secret assignment. He is to find a notorious French agent who has been causing a lot of trouble for the British in Spain. This Frenchman will not hesitate to torture, and then kill, Nicholas if he is discovered.
This is an excellent start to a series. It has adventure, high society, danger and lots of seduction. There is also a lot of good storytelling. It is very much worth reading.