This cult horror film from director Lucio Fulci lurches along with a certain amount of disjunction due to cutting, perhaps, if not to an innate Fulci disposition.
When the Boyle family temporarily moves into a mansion near Boston so the father can do some research, the son Bob (Giovanni Frezza) starts seeing the ghost of a young girl motioning to him, and eventually he discovers the basement's terrible secret. A certain Dr. Freudstein (Giovanni de Nari) has been hanging out there since 1879 when he was banned from the medical profession, and he has kept himself alive although in miserable physical shape, by murdering the various inhabitants of the house and using their cells to keep his body going.
An oversize bat attacks the father, floors come apart and crush unsuspecting victims, and at one point little Bob's blond head is held to the basement door by the evil doctor while the father is wildly swinging his axe through the door to save his son.
Scenes like these and others are the real objective of the movie -- the strange and irresolute ending, and leaps and gaps in the plot, are indications that all else is dispensible pretext - gore is the goal and it is delivered in sickening doses.