Following the death of his mother and brother in the outback, Cosmo Curtoys is sent to Oxford from Australia, to live with his aunt, Eunice Doom, a Professor of Mathematics. During the week he attends a boarding school in Oxford; at weekends, he returns with Eunice to the family home at Curtoys Mill. He learns that his family is cursed. In the days of the Roman occupation of Britain, a Roman soldier killed the son of a priestess of a British forest deity, for neglecting the worship of Mithras, and killed the boy’s mother when she came to his defence. Her mother (and the boy’s grandmother) cursed the Roman soldier: every generation hence would lose its first-born son in warfare or fighting, and his mother not long after.  

Eunice explains that Cosmo’s father had moved his family to Australia in an effort to outrun the curse. However, after consulting a local Aboriginal elder who confirmed that the curse would still be in effect, Cosmo’s mother and his brother, Mark, made the decision to break the line of the curse, by walking out into the desert and dying on their own terms.

As Cosmo grapples with this knowledge, and with his own grief, he finds that Curtoys mill is haunted. He meets several ‘shadow guests,’ all older sons who would have been killed by the curse. Con, a Roman-era boy, who gets Cosmo to help him train for battle in the gladiatorial arena; Sim, who needs help preparing to go to the Middle East on a Crusade; and 18^th-century Osmond, who with his mother, a striga, or shape-shifting witch, attempted to thwart the curse. While Con and Sim are benign, Osmond and his mother are not, believing that by killing Cosmo, they will return to life. Osmond challenges Cosmo to a sword fight in the old mill; Cosmo is saved by an old coin on a thread around his neck, but nearly drowns when the floor of the mill gives way. He is rescued by Eunice’s elderly St Bernard, Lob, who gives his life to save the boy.

As the tension mounts throughout the novel, Cosmo is attacked by poltergeists. He discusses temporal disturbances and other supernatural events with Eunice, a mathematical genius who is open to the idea of ghosts. The novel concludes on a note of resolution: Cosmo’s presence has both called the ghosts into action, and helped lay them to rest. His father returns from Australia and settles at the Mill; Cosmo looks forward to a new term at school, where he has initially suffered ostracism but has survived it and made friends.  

The Shadow Guests is a ghost story that explores several ideas: of curses, of love, of loss, of grief and recovery, and of the nature of time and of the paranormal.  Aiken draws on British history to establish the ancient curse that is the main problem of the novel: its origins in the invasion of Britain by Romans is intriguing, suggesting that the novel has some sensitivity to the complexities of history: who is at the root of the curse? The old woman who curses the Roman soldier, or the soldier who has killed her mother and son? Cosmo’s encounters with different cursed children from different periods (Con, Sim, and Osmond), gives him insight into the impact of the curse, and into the actions of his mother and brother. These figures draw on the longue durée of British history, and underscoring the idea of Britain as a land that is imbued with history, with magic, and with the supernatural. Its Roman history is part of that extended heritage, as is the pre-Christian curse of the old British woman. While the discussion of time is not always convincing, what is attractive about this novel is the way that adults and children work together to solve challenges, and the sense of family unity that is recovered by its conclusion.