The Rossetti Letter by Christi Phillips (2008) skillfully combines the stories of Venetian courtesan Alessandra Rossetti, who broke the Spanish Conspiracy in 1618, and modern-day American graduate student Claire Donovan.
Alessandra and Claire's stories and motivations unfold in alternating pieces as Claire heads to Venice as the chaperone for a teenager, but truly to uncover the story of what happened in 1618 in order to finish her dissertation. Add the pressure of a professor with a book ready to publish saying that Alessandra actually served as a co-conspirator in the plot to take over then-independent Venice.
And the descriptions of Venice--sigh.
My overall personal rating of The Rossetti Letter is a B.