The Forgotten Boy — Laura Andersen

A building undergoes multiple transformations through the centuries -- but a fair-haired boy continues to haunt its halls . . .
 
1460: Ismay Deacon, caught between sides in the War of the Roses, tries to hide away in her ancestral home, Havencross. But when word gets out that she has a child, and speculation on who the father might be, Ismay has to make a terrible choice to protect her son. The Deacon family disappears, but there are rumors of a fair-haired, unsmiling ghost of a boy haunting the halls of Havencross . . .
 
1918: War nurse Diana Neville is hired by Havencross School for Boys to run the infirmary. She's enjoying the change from the front lines -- but soon, vials are smashed in the infirmary when no one is there, there is knocking on her door in the darkness, and she hears footsteps in empty corridors. Moreover, the youngest students are reporting a ghostly boy luring them from bed in the middle of the night. But as Diana tries to investigate, she is faced with an outbreak of the Spanish flu, a child's disappearance, and a journey into terrifying medieval tunnels.
 
2018: Juliet Stratford is hired to spend the winter at Havencross to clear it out before it becomes a luxury hotel. Juliet, a historian, throws herself into the mysteries of the estate. Who is the forgotten boy who has haunted Havencross for so long? And is it the same boy that Juliet has begun to see in the echoing, empty house?