Giles's short novel holds secrets and lies concerning nine-year-old Samuel Clay, who is currently ensconced in Braddon Hall, a rather formidable family home in rural Surrey. As Samuel observes the bleeding light that seems to "throw smoky shadows" across the face of Ruth, Braddon Hall's housekeeper, he knows he must try to be good for Ruth, the only person at Braddon Hall apart from cook Olive, who comes once a week, and groundskeeper William, who does what he can with the garden on Wednesdays.
Samuel misses his mother who is currently away in America. On his atlas with its crowd of pins topped by tiny green flags, Samuel marks all the places his mother has been on her journey. He also likes to look at her series of postcards. He solicits advice from his best friend, Joseph, on how best to handle Ruth, whose face is locked in a perpetual grimace: like a queen "making a decree that certain topics had reached their end."
The acting out between Ruth and Samuel becomes a sort of violent dance, the boy ever-more paranoid every time he says things and does things that make Ruth cross. Ruth's lips are constantly pursed in condemnation as she stands in the middle of his mother's bedroom, reading her private letters. Samuel knows that adults have their secrets. He begins to see Ruth as a "nasty beast who should be thrown down a well or locked in dungeon." The tighter the yarn pulls, the harder Samuel wills himself to resist it. Ruth only sees the wrong that she thinks Samuel has done. His head full of sorrows, Samuel stands by the window with his arms folded, scowling out at the darkness. His mum went away in the dead of night, "all of a sudden with no warning and no goodbyes," and the only person to see her go was Ruth.
Shepherding a pervasive ambiguity, Giles constructs a gothic tale rife with uncertainty about aspects of Samuel's putative reality. Afraid of the dark, "a great veil of shadows" embraces Samuel. He's haunted by Joseph's story of a housekeeper who murdered the family she worked for and hid their bodies in the cellar. The family had vanished in the night, the trusted housekeeper the only witness. Samuel doesn't want to believe tjat his mother is dead; he wants to believe what Ruth tells him--how she misses his mother too and how murder "is not one her sins."
"I won't allow you to wallow in the foul waters of deceit." Samuel and Ruth inhabit a world enveloped illusion. Samuel has a sense of something passing between Ruth and William that isn't about "trimming lawns and paying wages." He sees the nasty glint in Ruth's eye, lost in the wilderness of his troubles. Perhaps Ruth really is a monster whose cruel heart "swells with gladness at every suffering." Perhaps she really loves to cut throats and "strip the fur from flesh."
Though the ending offers no real resolution, Giles's sensitive portrayal of Samuel sells his mystery of a boy tossed about by the winds of assumption and gauzy half-truths, made all the darker by Ruth's disquieting air and her supercilious lack of compassion.
The Boy at the Keyhole keeps the reader off-kilter as it unfolds along the search for the truth of what exactly happened to Samuel's mother. The novel stays suspense-filled until the sinister end, Giles luring the reader through his elegantly told story in language so poetic that it is its own reading experience.