The Turner Erotica, a biographical novel by Robert J. Begiebing.

J. M. W. Turner (1775-1851), the greatest British landscape painter and one of the most revolutionary influences on Western art since the eighteenth century, left upon his death a rich and varied legacy to Britain’s National Gallery, including more than 19,000 sketch studies containing considerable erotica.  
When John Ruskin, Turner’s greatest supporter at the time, discovered the erotic works, he, with the help of National Gallery Keeper Ralph Wornum, burned most of the material they found offensive.  
The Turner Erotica  follows narrator William James Stillman (the young American artist, consul to Rome and Crete, friend of Ruskin, and acquaintance of Turner) as he pursues a dangerous quest across Britain, Europe, and New England to discover and save the few remaining studies that through theft and betrayal escaped Ruskin’s outraged fire.  In his quest, Stillman enlists the help of Pre-Raphaelite William Rossetti, the liberated American painter Allegra Fullerton, and Sir Richard Burton (the greatest linguist, swordsman, pistol-shot, and covert agent for the British government in the 19th century).  
Stillman’s obsession with the surviving erotic studies arises out of their potential value to British art history and his deep sense that the studies contain a secret clue to the master’s celebrated body of public work.