Details are foggy, but I think the background is that a young woman (played by a blond actress I think) was living with a couple, either her friend or sister and friend/sister's boyfriend, with whom she'd had an affair. She gets kicked out and is adrift...seems like she takes an odd job or something that requires her to go check on this man she doesn't know at his home. (He is a truck driver who lives alone in a house, remote from town). She gets there and is overpowered and held captive by this shaggy-looking guy (bearded, long hair unkempt, explosively moody and scary). He calls her by his ex-wife's name and insists she is her, and intends to make her stay with him until she realizes she still loves him. He ties her up and leaves her alone sometimes, and when she gets loose she still can't escape because of his huge dog that guards the house. Later she manages to trick him into thinking she is pregnant and calling her a doctor The doc (who knows the man's case and realizes what's going on) almost rescues her, but he has a heart attack and dies. Later she does escape, but in a twist of plot, she returns ties him up, forces meds into him, and takes care of him. Later, when the real wife returns, here's where my memory is sketchiest, I think blondie kills the bitchy real wife and buries her on the property and helps the now meek and lucid husband evade police inquiries by pretending to be his wife.