This is a very well made thriller that starts off as a murder mystery and then takes a turn into pure horror.
Three trustees are killed and everyone thinks all three of the are suicides. However, when a bus goes up in flames and three others very rich trustees are killed, then some people suspect something is very wrong.
A young doctor who is treating a child who was on the bus knows there is more to the story about what happened, but cannot break theu the mental block the young girl has set up in her mind.
The girls mother, Anna Harb (Diana Dors) comes to claim her but is met with resistance from both medical staff and the orphanage where she has been living while her mother was in prison.
A pathologist (Peter Cushing) and Colonel Bingham (Christopher Lee) manage to uncover a very sinister plot involving older people living forever after entering a young person's body.
As I said, this is a very well made film that keeps going straight on until the end, and then it really pulls out all the punches. This kind of film has been made before and it reminded me of the basic plot premise behind such films as "Brotherhood Of Satan" but done with a slightly different twist element.
The ending to this film is very bleak and depressing, but that is the only way a movie like this could have ended. HIGHLY RECOMMENDED!!