Based on the novel by Fred Mustard Stewart, pic follows in deadpan style the antics of a deranged concert pianist (Curt Jurgens), dying of leukemia whose lust for his daughter (Barbara Parkins) and devotion to devil-worship destroy the marriage of writer Alan Alda and Jacqueline Bisset.
To revive his sexual prowess, Jurgens has Alda killed, then assumes his body. A trifle slow on the uptake, Bisset finally realizes something is amiss after her daughter dies under mysterious conditions. Alda-cum-Jurgens starts getting ruthless in bed, and the ex-husband of Parkins (Bradford Dillman) tells her (before being killed) of a monster child miscarried by Parkins and sired by her father.
Main fault is a tired script with more than a full quota of arch, laughable dialog, spouted with relish by performers struggling to keep their heads above water.