 The children learn that A Lady Writing was traveling from The National Gallery of Art in Washington D.C. to Hyde Park . The next day there is a story in the paper of how the painting mysteriously disappeared . A letter from the thief appears in the newspaper , telling the public that he will not give back A Lady Writing until they prove which Vermeer paintings were truly painted by him . This sparks worldwide uproar . Calder and Petra investigate as their friendship grows . Mrs. Sharpe requests police protection and it is revealed that she and Ms. Hussey were two of the three recipients of the thief 's letter . Calder and Petra eventually conclude that the painting is hidden in the local Delia Dell Hall , and they sneak out and find it . They barely escape from the thief , who is later found dead from a massive heart attack on the train by the police . They learn that the man is Xavier <unk> , also <unk> as Glitter Man , who was posing as Tommy 's stepfather under the name Fred <unk> . A known art thief , he was asked to steal the painting and sell it for sixty million dollars . The other recipient of the letter is revealed to be Mr. Watch . 
