Nothing But the Night (1973)

When the daughter of an ex-con under the care of orphanage run by a powerful, upper class trust is injured in a bus crash, several suspicious details come to light. As a psychologist and a journalist investigate potential trauma in the child's past, high profile Police Colonel Bingham (Sir Christopher Lee) enlists the help of his friend, prominent pathologist Dr. Ashley (Peter Cushing), to identify the incident's connection to a series of "accidental" deaths amongst the wealthy members of the trust's governing board.