An isolated castle, a deadly crime. Is this real or a nightmare?

In a remote castle high up in the Tuscan hills secrets are simmering among its glamorous English residents:

The ailing gentleman art-dealer
His dazzling niece
Her handsome Fascist husband
Their neglected young daughter
The housekeeper who knows everything
and Connie, the English widow working for them.

Every night, Connie hears sinister noises and a terrible wailing inside the walls. Is she losing her grip on reality?

Or does someone in the castle want her gone?