“A panel of the 15th century painting Adoration of the Mystic Lamb disappeared from Ghent in 1934, and only a few clues were left behind. But on Friday, an engineer claimed that he had solved the riddle left behind after the disappearance. Gino Marchal, co-author of The Fourteenth Letter, claimed that the panel is hidden under a square in the Kalandeberg area of the city centre — where the mayor is now urging treasure hunters not to dig.”