The priceless Revolutionary era sideboard willed to the Wellington School for Girls is missing. The school authorities presume it never even existed, but Felicia Cartright is sure it is real and can be found. She persuades her two friends, Gretchen and Joan, to go with her to Maine to spend their school break looking for the sideboard. They find they are up against several obstacles: a two-week deadline, antagonistic caretakers, and a mysterious code which could be the key to it all.