[Off-topic] !PANDA:
I havnt watchd the film, but wiki is pretty useful- "The film opens in a Seattle Bellevue neighborhood with Henry Morrison, a psychotic serial killer and master of disguise, washing blood off himself in a bathroom before shaving his beard, replacing his glasses with contact lens and putting a few of his belongings into a suitcase. After packing his things, Henry leaves through the front door of his house, nonchalantly passing the butchered remains of his family, Vicki, Jill and a grown male relative along with a grown female relative, whom he had earlier murdered. Boarding a ferry, Henry disposes of the suitcase containing the objects from his former life by throwing it into the ocean.

One year later, Henry (operating under the identity of a mild-mannered real estate agent named Jerry Blake) has married the widow Susan Maine. Jerry's relationship with Susan's teenage daughter Stephanie is strained, as Stephanie is highly suspicious of Jerry, despite his acts of kindness, such as giving her a puppy as a gift. After a session with her psychiatrist Doctor Bondurant, who advises her to give Jerry a chance, Stephanie is driven home by Jerry, who suggests they work together to build a better relationship, also stating that he and Susan hope she will try to be a better student at school, where Stephanie is having trouble.

In Seattle, vigilante drifter, former adventurer and amateur detective James "Jim" Ogilvie, the brother of Jerry's latest victim Vicki and Jill's young uncle, convinces a reporter to run an article about his sister's slayer in the newspaper. While hosting a neighborhood barbecue, Jerry discovers the article and is clearly disturbed by it. Excusing himself from the festivities, Jerry goes into the basement of the house and begins maniacally rambling to himself (possibly recalling memories of his unhappy childhood), unaware that Stephanie is in the basement as well. Discovering his stepdaughter's presence, Jerry brushes off his outbursts by saying he was simply letting off some accumulated stress. Leaving the basement, Stephanie finds the newspaper mentioning Jerry's earlier killings and comes to believe her stepfather is the murderer Henry Morrison mentioned in the article.

Stephanie writes a letter to the newspaper requesting a photo of Henry Morrison; but Jerry finds the photo in the mail and hides it from Stephanie while she is with Dr. Bondurant. After hiding the photo, Jerry thrashes about in the basement and contemplates killing Susan and Stephanie, but is brought to his senses when Susan yells to him, saying that Dr. Bondurant is calling asking to speak to him. Jerry refuses to answer the phone, having Susan tell the doctor that he is out. Curious as to why Jerry is avoiding him, Doctor Bondurant pretends to be a man named Ray Martin and calls Jerry at the real estate agency under the pretense of wanting to buy a house. As Jerry schedules a meeting with Bondurant, Stephanie opens an envelope addressed to her in the mail and finds a fake photo of Henry Morrison that Jerry had planted to protect his identity. Stephanie is tricked into believing her suspicions of Jerry are false.

During his meeting with Bondurant, Jerry becomes increasingly suspicious of the man, who continually questions him about his home life. Realizing Bondurant is not who he says he is, Jerry beats him to death with a wooden board. After discovering Bondurant's identity as his stepdaughter's psychiatrist, Jerry makes Bondurant's death look like an accident, blowing up the doctor's car with his body inside it. The next day, Jerry informs Stephanie of Bondurant's death in an apparent car accident and succeeds in bonding with the mournful Stephanie. Jerry's newfound relationship with his stepdaughter is quickly cut short when he catches Stephanie kissing her boyfriend named Paul Baker, who is also the family friend of the Maines before Jerry came. Jerry's wild accusations of Paul attempting to rape Stephanie result in him getting into an argument with Stephanie and Susan, which results in the former running off. Realizing all hope of having a happy life with Susan and Stephanie has been ruined, Jerry quits his job and creates a new identity for himself as Bill Hoskins, applying for a job as an insurance agent in another town, where he begins to court another widow while planning to get rid of Susan and Stephanie.

Having discovered where Jerry is now living, Jim Ogilvie begins going door to door through town in search of his former brother in-law. After Jim stops by, Susan phones the real estate agency to tell Jerry that someone was looking for him, only to be informed that Jerry had quit several days ago. Confronting Jerry when he returns home, Susan is told by Jerry that there must have been a mix-up. While explaining himself to Susan, Jerry confuses his Jerry Blake identity with the new Bill Hoskins one he had crafted and bashes Susan with the phone before knocking her down the basement stairs after she realizes Stephanie was right about Jerry. Content that Susan is dead, Jerry then sets to kill the family puppy, however, he instead prepares to kill Stephanie when she returns home and begins showering when Jim knocks on the door, having concluded that Jerry is Henry Morrison.

Ambushing Jim when he enters the house after recognizing him, Jerry kills him by stabbing him in the stomach with a knife as Jim pulls out a Smith & Wesson Bodyguard .38 Special snubnosed revolver before attacking Stephanie. Sustaining a wound to the arm when Stephanie stabs him with a piece of glass, Jerry follows his stepdaughter into the attic, where he corners her. Before he can kill Stephanie, Jerry falls through the weak floor of the attic, but recovers from the fall quickly and renews his attack on Stephanie when she tries to escape. Before he can harm Stephanie, Jerry is shot twice by a still living Susan, who had regained consciousness and retrieved Jim's gun. Feebly trying to reclaim his knife after being shot, Jerry is stabbed in the chest by Stephanie, who grabs the knife before he can. Uttering a weak "I love you" to Stephanie, Jerry falls down the stairs, seemingly dead. The film ends with Stephanie cutting down the birdhouse she and Jerry had put up during the brief time they had bonded with one another."