I remember watching an old horror film about 40 years ago – the opening scene was a mad scientist who had a red-haired (?) woman on a laboratory table and he had hooked up some kind of billows type pump to transfer her blood to something / someone else…
An angry mob appears at the front door of the castle (?) and the mad scientist leaves the secret laboratory to see what all the noise is about and gets dragged off by the mob.
Flash forward: An American (I seem to think) somehow inherits the castle and comes to visit. As he's looking around, he touches a metallic silver ornament that looks like a skull with wings (?) and a bookshelf opens – revealing the entrance to the secret laboratory!
He enters the creepy laboratory and the camera (with scary music) suddenly pans to the skeleton of a woman with red hair (?) still strapped to the laboratory table!
At that point, I ran out of the house – and never found out what the movie was!