The Case of the Piggy Bank Thief — Martha Freeman

Although a stolen piggy bank is normally no big deal, this particular bank belongs to seven-year-old Tessa, whose mother is the president of the United States. When her eleven-year-old sister, Cammie, finds out that the piggy also held an old coin their dog, Hooligan, dug up from the White House lawn, the case really gets complicated--and delicate. The coin in question, they realize, is probably the one archaeologists have been trying to uncover and is worth millions! The girls have got to find the culprit and the coin and turn it in or their mother will have a major scandal on her hands.