Nancy's best friends, Bess and George, may never speak to each other again. It all started because Bess wanted to jump rope. SHe asked George to hold on to her beautiful heartshaped locket. George put it in her book bag to keep it safe. But when she went to give the locket back, it was gone! Inside the bag, Nancy finds a clue to the missing locket, a sandwich. And not just any sandwich: a peanut butter, mustard, ketchup and relish sandwich! It's a mess of a mystery, but finding out where the sandwich came from may be the only way to get Bess and George to make up.