From back of book:

Florence: Harvard symbologist Robert Langdon awakes in a hospital bed with no recollection of where he is or how he got there. Nor can he explain the origin of the macabre object that is found hidden in his belongings. A threat to his life will propel him and a young doctor, Sienna Brooks, into a breakneck chase across the city. Only Langdon's knowledge of the hidden passageways and ancient secrets that lie behind its historic facade can save them from the clutches of their unknown pursuers. With only a few lines from Dante's The Inferno to guide them, they must decipher a sequence of codes buried deep within some of the Renaissance's most celebrated artworks to find the answers to a puzzle which may, or may not, help them save the world from a terrifying threat.

Left in the fiction section with all the other Dan Brown books.