The ghost of murdered Sylvia Whichcote has been sighted prowling the grounds by Frank Oldershaw, a disturbed fellow commoner. When his anxious mother employs John Holdsworth, author of The Anatomy of Ghosts - a stinging account of why ghosts are mere delusion - to investigate the sighting, the uneasy status quo at Jerusalem is rapidly torn apart.
Holdsworth grows to realise that the sinister Holy Ghost Club governs the privileged life at Jerusalem with a rigour far more effective than anything the Master, Dr Carbury, could muster. And when Holdsworth finds himself haunted - not only by the ghost of his dead wife, Maria, but also Elinor, the very-much-alive Master's wife - his fate is sealed. He must unravel the circumstances surrounding Sylvia's death . or the hauntings will continue.