Throughout the novel, James Robertson provides evidence which could either point to Gideon Mack’s story being the account of a person of completely sound mind, or the delusions of someone who has lost touch with reality. Ultimately, he leaves the reader to weigh up the evidence and make up their own minds about the truthfulness of Gideon’s manuscript.
Gideon’s claims about the sudden appearance of the standing stone in Keldo Woods seem fantastical. No-one else seems to be aware of it. His story about being rescued by the Devil at the Black Jaws and his subsequent close friendship with this figure are equally unbelievable. This could point to his story being:
a tissue of lies or the fantasy of a damaged mind
On the other hand, doctors are unable to explain how Gideon could have survived three days in the Black Jaws relatively unscathed. His scarred and damaged leg is also hard to account for. And Elsie Moffat reveals to Harry Caithness that she also saw the standing stone.
After his revelations at Catherine Craigie’s funeral, the verdict of the people of Monimaskit is that he is mentally ill and he becomes a figure of derision and pity in the town, his reputation completely destroyed.
The people who knew Gideon also speculate on his mental health during their interviews with Harry Caithness. Of all the people who knew Gideon, Elsie Moffat is the only one who believes he was telling the truth as
he had nothing to gain by lying.
Gideon himself is adamant that he is not mentally ill and he is certain that he did discover the standing stone and that he did meet the Devil.