Lady Debra Seeley owns an ancient druid castle near her property. When people are killed by ghosts of druids who used to live there, Lady Seeley is called upon by the mayor to put a quit to the issue. She leans on Christopher Fenn to assist with the problem. Fenn arrives with his dog Drum. Fenn also brings and his invention, a dematerialization machine, to turn all three of them into immaterial 'ghosts'. With a branch of holly with which he calls upon for protection, he confronts the druid ghosts with Lady Seeley and Drum at his side.