Michael Dixon relocates to the small town of Ashcott with his mother after his police officer Father's murder in London. The small house is turning into something of a building site thanks to his Mother's new love Gary. Gary is the worst plumber in the history of the building trade and seems incapable of sticking to a plan. Wherever he goes, chaos, destruction and irate customers follow.

Depressed with the situation and as lonely as ever, Michael is at least blessed with the same sharp analytical brain as his Father. He develops a deep affection for History teacher Professor Julian Fothergill. They are both swots, interested in local history and have a fascination with stone circles. Days out with the kindly old man are about the only high in his life and the one thing keeping him sane until the professor is killed in a suspected hit and run one night while on the way to visit his sister Annie. He leaves Michael an interesting folder in her care, concerning a mysterious stone circle he has discovered in the grounds of Markham Hall, a rundown local mansion built in the 1840s.

Michael examines the site of the alleged accident and concludes the Professor was murdered. Realising the Police are going to do nothing apart from keeping an eye out for a lorry they suspect was involved in the accident, Michael takes the bold step of publishing his findings in the school magazine. The move causes a major backlash and Michael is expelled. Now, with time on his hands, he is able to devote all his efforts to discover how the Professor died.

A foolish night time visit to the derelict house with his friend Grant Ryman ends with Michael being stalked through the grounds by a mysterious black swirling fog and he soon realises the strange stones have an occult significance.