The Mysterious Strangler — Peter J. Heck

A trip to sunny Florence provides a welcome change in the weather for Mark Twain and his family after a lecture tour of England. And Twain's assistant, Wentworth Cabot, gets some much needed rest and relaxation while the Twains set up house.

Falling in with a charming group of Americans abroad, Cabot whiles away the hours touring museums and discussing art in a local cafe. But when a recently discovered Raphael masterpiece is stolen during a dinner party they are attending, Cabot and the irascible Twain set out to find the painting--and the lovely young woman who disappeared along with it...