Lavinia Lake and Tobias March series

Amanda Quick's bestselling trademark is a combination of suspense and passion in historical tales alight with sparkling wit and brimming with dangerous intrigue. Now she serves up the most tantalizing novel of her career as an enterprising woman allies herself with a mysterious spy, only to be caught in a seething brew of treachery — and temptation....
From the moment he burst into her antiquities shop in Rome, Lavinia Lake knew the stranger...

Regency sleuths Lavinia Lake and Tobias March stumble into the middle of a deadly mystery as they become caught up in the search for a killer who targets wealthy older men on the brink of marrying beautiful, much younger women.