An anonymous diary is a mystery with handwriting that is difficult to decipher. It is filled with technical drawings and chemical formulas. Was the destructive explosion an accident or an act of revenge?

A suspicious stranger -- An excitable driver -- The diary -- The initialed ring -- A dangerous detour -- Nancy's strategy -- A disclosure -- Worried sleuths -- A scare -- A spooky shack -- Lost in the crowd -- Incriminating evidence -- The law takes over -- An arrest -- Nancy is accused -- A new assignment -- An important clue -- A revealing translation -- Setting a trap -- A surprising victory.