The House of Eyes — Thomas Bloor

Set three years before The Memory Prisoner starts, Maddie is still deep in her self-imposed incarceration in her family home. A recent burglary has caused unease. Various items were stolen, including a framed photo—the only picture the family has of the children's father, Quentin Palmer. Neither Maddie or Keith have any memory of him, and Mrs Palmer never speaks of him, except to say he's away on business. But then one foggy night there's a knock at the door. The errant father has returned—or has he?