Stravaganza: City of Masks by Mary Hoffman
Yes, this is a YA / children’s book, but don’t let that put you off. I’m sixty pages in and totally hooked.
The blurb on the back: Imagine you are one moment ill in bed, and the next transported to a world that is awash with deception, intrigue, and glamour. In a spine-tingling discovery, Lucien discovers that he is in fact a ‘Stravagante’ and with the help of a talisman can transport himself to sixteenth century Bellezza, a city inspired by Venice, and filled with unexpected danger.