When the Hatts, a family that disappeared years earlier under mysterious circumstances from the old Stoneybrook lighthouse, suddenly return and move in with the Kishis, Claudia wonders what secret they are keeping. Ann M. Martin is the creator of The Baby-sitters Club, which has more than 190 million books in print, making it one of the most popular series in the history of publishing. Her novels include A Corner of the Universe (a Newbery...