The Cracks by T.H. Huddleston

Following the death of her husband, Sandra Riley is left all but destitute: jobless, penniless and about to lose her home. But an encounter with an old university friend seems to offer a lifeline. Gerry McManus was always well-to-do; now he’s risen to join the landed gentry, as his wife Joy takes possession of her aristocratic family’s remote, dilapidated but undeniably impressive stately home: Hautmond Hall.

Accepting Gerry’s invitation, Sandra arrives at the house intending to gather her thoughts, face her grief and plan her next move. But life at Hautmond isn’t so simple. Why is she having such dreadful dreams? Why do visitors to the house keep suffering inexplicable accidents? What’s hidden in the secret room buried deep in the lightless cellar? And who are the distant, shadowed figures she keeps glimpsing in the mirrors?

As the truth about Hautmond Hall begins to reveal itself – and as her relationship with her hosts shifts inexorably from mutual support to something more complicated and transactional – Sandra will find herself trapped inside a waking nightmare, one that has afflicted generations of desperate people before her.