Landscape of Lies — Peter Watson

A mysterious painting holds the clues to a cache of priceless relics in this treasure hunt of “deepening suspense” à la The Da Vinci Code (Library Journal).
 
In financial trouble, Isobel Sadler considers selling a painting that's been in her family for generations. She can't imagine it's worth much . . . until someone tries to steal it.
 
Mystified, Isobel turns to art dealer Michael Whiting for advice. He identifies the painting as a sixteenth-century treasure map pointing the way to a series of lost religious artifacts hidden by monks when Henry VIII dissolved the monasteries. If he and Isobel can decipher the clues in the painting, Michael reasons, her money troubles will disappear.
 
But if they can't decode the painting quickly, Michael and Isobel could be history themselves. As they struggle to translate the arcane instructions -- laced with references to everything from the Bible to Botticelli -- they are stalked by a rival who will stop at nothing to get his hands on the treasure.
 
Peter Watson's stylish art-world thriller seamlessly mixes action with “sustained literariness, refinement, and polish” (Library Journal).