When Nancy`s best friends, Bess and George get in a fight, Nancy thinks that there is NO way out of it. George was holding Bess`s locket, and when she went to get her backpack, it`s gone! Bess and George don`t want to talk to each other, and Nancy knows she can do something. But she doesn`t know what. After talking with Bess, Nancy starts to see more of what she can do. The girls don`t know who did it, or what happened. But after awhile, when the class field trip comes around, Nancy and another girl in her class get their lunchboxes mixed up. When they find out Ned Nickerson has the same backpack as George, and they get them mixed up, the mystery of the lost locket has been solved!