the Secret Old Attic (Nancy Drew Series #21)

Nancy Drew races against time to unravel the clues in a dead man's letters. If she succeeds, Philip March and his little granddaughter can be saved from financial ruin. Following the obscure clues, Nancy undertakes a search for some unpublished musical manuscripts which she believes are hidden in the dark, cluttered attic of the rundown March mansion. But someone else wants them enough to put many frightening obstacles in Nancy's way.