It's the night of 12 November 2019. The worst flooding in 50 years hits the city of Venice. 85% of La Serenissima is underwater. Gale force winds roar across the lagoon and along the narrow streets. And the body of Dr Jennifer Whiteread- a young British art historian, specialising in the depiction of angels in Venetian painting - is found floating in a flooded antique bookshop on the Street of the Assassins.