Nancy searches for clues to missing music manuscripts in love letters written by a deceased soldier. This soldier’s elderly father and young daughter are sole survivors of a once prominent family. The Marches, inhabitants of a run-down family estate, are facing financial ruin. The old man believes some of his son’s music is being sold and played on the radio. Nancy, Bess and George go to the estate to investigate. In the meantime, a client of Nancy’s father turns to her to examine a competing company he believes is using his patented production methods illegally. As Bess and George prepare for an important Emerson College dance, they are bothered that Ned has not asked Nancy! He frequently seems be in the company of a snobbish socialite! Nancy investigates both mysteries, ponders her friendship with Ned and discovers hidden songs in the spooky attic. Clues lead her to a music plagiarist and a chemist with a stolen formula. Nancy learns that both are the same dangerous criminal!