Nancy Drew #9: Ghost in the Machinery

Has Nancy Drew solved the world's energy crisis?  On a mission, sponsored by young, rich, and handsome Ralph Credo, Nancy teams up with eccentric scientist Roy Hinkley, to find an amazing high efficiency engine able to operate at an amazing 200 miles per gallon!  The experimental engine, mounted on a tank, was part of an experiment during the final days of World War II.  There's just one problem, the engine and the tank are haunted.  "Ghost In The Machinery" is the first in a series of three Nancy Drew adventures entitled "The High Miles Mystery."