Dark Places (1974)

After moving in to a dilapidated mansion, left to him by a mental patient, Edward Foster starts noticing strange occurrences and hearing ghostly voices. Soon, he starts being possessed by the spirit of Mr Marr, the dead original owner, and the story of how his wife and children die is gradually revealed. Marr was planning to leave his family (mistress in tow) and had emptied his bank account, hiding the money somewhere in the house before going insane. The local doctor and his sister, along with Foster's solicitor, Mr Prescott feign friendship with the new owner, but all they want is to find the money.