The Screaming Skull (1958)

Newlyweds Eric and Jenni Whitlock retire to his desolate mansion, where Eric's first wife Marianne died from a mysterious freak accident. Jenni, who has a history of mental illness, begins to see strange things including a mysterious skull, which may or may not be a product of her imagination.

Suspicion falls on Mickey, the estate's mentally challenged gardener, who was seemingly was very attached to his former mistress.