The #1 international bestselling crime thriller that introduces Belgian detective Pieter Van In, “a brusque cop with every bad habit you can think of” (The New York Times Book Review).

The beautiful medieval architecture of Bruges belies the dark longings of her residents. When the wealthy and powerful Ludovic Degroof’s jewelry store is robbed, nothing is stolen, but the jewels have been dissolved in jars of aqua regia, an acid so strong that it can melt even gold. In the empty safe is a scrap of paper on which a strange square has been drawn.

At first, Inspector Van In pays little attention to the paper, focusing on the bizarre nature of the burglary. But when Degroof’s children begin to receive letters with this same enigmatic square, Van In and the beautiful new District Attorney, Hannelore Martens, find themselves engaged in solving the mystery of a complex web of Latin phrases, a baroness’ fallen family, and Degroof’s unsettling relationship with a hostage grandchild, who is being ransomed for a priceless collection of art.