Artist Lucy Moon learns a centuries-old cupboard has turned up in the town dump that may conceal a priceless artwork?Leonardo's study for his masterpiece, Mona Lisa. Missing for over four hundred years, the drawing is said to hold a valuable secret?the identity of the woman in the iconic painting.

The mystery surrounding the lost study ignites Lucy's curiosity. With the help of her husband and a small group of friends, she begins a search for the drawing. When William and Amelia Smythe arrive in town claiming to be art collectors, Lucy discovers they're after the treasure, too, and their calling cards are deception and murder.

Lucy clashes with the treacherous couple at every turn but she is determined to outwit them and find the artwork before it falls into their hands, where it would remain lost to the world forever?again. In a final, explosive confrontation with the Smythes, she risks everything to preserve the drawing and reveal Mona Lisa's true identity.