Brian De Palma got the idea for Sisters, the film that put him on the map, after reading an article about a set of Russian Siamese twins.

Haunted by a photo of the siblings in which one of them had, as he puts it, a "surly, disturbing look on her face" while the other was smiling and looked healthy, De Palma was inspired by the piece which detailed the twins' psychological problems as they grew older.

He fashioned a script with Louisa Rose and came up with a film that paid homage to the work of Hitchcock, most notably Rear Window and PSYCHO. In fact, the director had the good fortune of hiring Bernard Herrmann to compose the score, quite a coup for someone so early in his career.

Philip Woode (Lisle Wilson) is appearing on a game show called "Peeping Toms." A hidden camera records him as he watches a beautiful "blind" woman named Danielle Breton (Margot Kidder) undress. The topic is chivalry and the contestants are asked to decide which course of action the man will take. Being a gentleman, he simply walks away. Neither contestant predicted the correct answer.

Danielle, an aspiring model and actress, is brought out before the audience followed by Phillip, who works as an advertising manager for a local newspaper.

For their participation, the two are awarded parting gifts. Danielle gets a new cutlery set, while Phillip, an African-American, is presented with a night of dining and dancing for two at Manhattan's "famous" African Room!

Outside the studio, Danielle asks if she can join him for dinner and he obliges. At the restaurant, the French-Canadian charms Phillip with her story of why she left Quebec and moved to New York City.

Their conversation is interrupted by Emil Breton (William Finley), Danielle's former husband, who tries to take her away with him. An embarrassed Danielle refuses to go and makes a scene. Phillip has a waiter escort her ex out of the restaurant and offers to take her home.

Danielle says she lives on Staten Island. "Staten Island? I thought you said you lived in New York?" Phillip asks. When she asks in return, "isn't Staten Island in New York?" Phillip's response is "I guess it is."

On the ferry to the outer borough, Phillip kisses Danielle after she tells him she hasn't been close to anyone since her sister left. They arrive at her apartment complex in the wee small hours of the morning.

Danielle is tipsy and proceeds to change quickly into her nightgown. While looking out the window, Phillip sees Emil standing near the building. Danielle says he's always following her.

Phillip pretends to leave by going back out and parking his car around the block. He then plans to come back through another entrance. The ruse works and Emil drives away.

Phillip makes love to Danielle on the sofa and they spend the entire night in the living room, although he is unaware of a huge, ghastly scar on the woman's leg.

The next morning, Danielle wakes up in a cold sweat. She goes into the bathroom to take some pills and sets two more aside on the sink. She then visits someone in the bedroom.

In French, she appears to be talking to her sister Dominique. Dominique is furious that Danielle has brought a man into their home. "Calm down, you know what the doctor said" Danielle tells her.

But Dominique is still angry and reminds her that the doctor separated them and put her in a hospital "full of lunatics." Danielle tells her not to ruin their birthday. The yelling wakes Phillip up and he can feel his back covered in scratches from the night before. He goes into the bathroom and accidentally knocks Danielle's pills into the sink while putting his shirt on.

Danielle is in tears and tells Phillip that her sister always gets jealous anytime she has a man in her life. She says her twin sibling is visiting because its their birthday. Phillip offers to leave but Danielle won't have it. She asks if he can do her a favor and refill her prescription from a drugstore.

After picking up the medication, Phillip decides to stop by a bakery to buy a cake. Elaine (uncredited) and Louise (Olympia Dukakis), the two women behind the counter, are bemused at his request to write a birthday greeting for the two sisters.

Meanwhile, Danielle calls Emil in a panic and tells him that she has only two pills left. When she can't find them in the bathroom, she falls on the floor, writhing in pain.

Phillip returns to the apartment, as Emil sits outside watching from his car. While Danielle is sleeping on the sofa bed, he goes into the kitchen and lights several candles on the cake. He carries it into the living room, along with a huge carving knife from Danielle's sparkling new cutlery set.

As he puts the cake in front of her, Danielle groggily picks up the knife. Suddenly she leaps up and stabs Phillip twice in his thigh, before jabbing the knife into his mouth and then tossing it across the floor. She then sits up in the bed in a daze, as a wounded Phillip crawls towards the knife.

Danielle (or is it Dominique?) jumps out of the bed and stabs him repeatedly in his back. Still not quite dead, the guy makes it to a window and scrawls the word "help" in his blood. Grace Collier (Jennifer Salt), a neighbor across the courtyard, sees him and calls the police.

Grace is a reporter for the Staten Island Panorama and she's written a number of unflattering stories about the police, including one entitled "Why we call them Pigs." Of course, this doesn't endear her to the authorities. She says that a man is bleeding to death and needs help. (The events are now unfolding in glorious split-screen)

We see Danielle wake up off the bathroom floor and assume Dominique committed the murder. Emil appears at the apartment and points out the body to Danielle, who hadn't seen it yet. Danielle mutters her sister's name and Emil asks if the twin is there.

Grace impatiently heads towards the scene of the crime as Danielle and Emil try to conceal what happened. They hide Phillip's body in the sofa and clean up the blood as thoroughly as they can, while Grace finds the name of the tenant on the mailbox.

Detective Kelley (Dolph Sweet) and his partner Spinetti (uncredited) meet Grace in the lobby of Danielle's building and she once again tells them that a man has been stabbed in one of the units.

Still smarting over her article and apprehensive about not having a search warrant, the two officers give her a hard time. Eventually they give in and Grace leads them to the apartment, just as Emil sneaks out to get rid of any evidence.

Danielle answers the door and lets Grace and the detectives in after some initial reluctance. They tell her the reason for their visit: the reporter witnessed a murder. Of course there's no sign of such a thing.

Still, Grace insists it happened and says the murderer was someone Danielle knows. "She was shorter and had a twisted face, and stringy hair and was having a terrible fit of some kind," she tells Detective Kelley.

Danielle denies having had anyone in the apartment and gives the excuse that she was watching a horror film, which is probably what made her appear jittery. She allows the three to search the apartment, unaware that there's a spot of blood on the back of the sofa. Grace, being the nosey reporter that she is, leads the search.

She notices two pairs of all the clothing in the closet and wonders if Danielle has a twin. Danielle denies this, saying she's a model and needs the extra outfits in the event something should happen to the first sets of clothing.

The officers wind down their search as Emil appears at the apartment. Grace has not given up and finds the birthday cake in the refrigerator with the names of the sisters written on it. "She does have a twin" she says before tripping and destroying her proof. Detective Kelly looks at her like she's a nut.

Outside the building, Grace vows to find out what happened, despite the fact that she's told the case is closed. Her mother (played by Mary Davenport) picks her up to spend the day with her.

In the car, Grace is distracted and has trouble paying attention to Mrs. Collier's smalltalk. Her mother tells her she has a good story that she should check out.

"An experimental madhouse" has opened in her neighborhood in which the patients live in "a family situation, just like real people." It's an arrangement that doesn't make her mother feel safe at night.

Grace notices the bakery she saw the name of on the cake box and asks Mrs. Collier to stop the car. Elaine and Louise confirm that someone bought a cake with two names scrawled on it.

Grace becomes agitated when her mother doesn't understand what she's doing, saying she wants to write more interesting stories than she's been given the chance to. "Are you on diet pills again?" Mrs. Collier asks. Grace is determined to get to the bottom of the mystery and makes a date with her mother for another day.

From a phone booth, Grace calls her boss to get the okay for her story. Her angle? "A white woman kills her black lover and those racist cops couldn't care less." She's given a green light and gets in touch with a private detective named Joseph Larch (Charles Durning).

Together, they watch for anything unusual from his van. Larch then tells Grace to go up to her place and signal him as to whether anyone is in Danielle's apartment. With her binoculars, she sees that no one is home.

The detective pretends to be a window cleaner and gets the keys from the super. Grace watches from her building as he looks around, until he finally finds a file which might be of interest. From the bedroom, Larch yells across the courtyard at her to meet him at his van. Suddenly, Danielle and Emil show up.

Grace tries not to panic and lets the phone ring once in Danielle's apartment, as a warning to Larch. Danielle and Emil are there with a moving company to have the sofa removed.

Larch meets up with Grace and tells her he believes the body is in the sofa, saying he tried to move it but it was too heavy. They follow the moving truck through the streets of Staten Island and onto the ferry to Manhattan.

Grace takes a look at the file and sees that it's filled with information about a set of Siamese twins who were profiled in an article in Life Magazine a year before. She plans to meet with the writer, while Larch heads for Quebec, which is where Emil told the movers to take the sofa.

The Life writer's name is Arthur McLennen (Barnard Hughes) and Grace visits him in his office. She pretends to be working on a follow-up piece to his story about the twins and shows him the file (from the Loisel Institute), which he remembers from his research.

McLennen has Grace watch a video documentary entitled Blanchion Twins Separated, which gives an overview of the Siamese twin phenomenon, as well as detailing the history of the sisters, beginning with their birth.

The first Siamese twins born in Canada, they were brought up in the Loisel Institute until adulthood. Doctors would not perform the operation to separate them for years, fearing they would be harmed by such a procedure.

The Director of the institute is seen talking about them and he observes that the sisters' psychological balance is fragile. He says his colleagues believe Dominique is the truly disturbed one but he thinks Danielle exists solely because of her sister. He's also shown talking to them just before the operation to separate them.

Grace finds the tape intriguing, but the writer tells her it's missing one major fact. McLennen says there were complications after the surgery and a nurse told him that Dominique Blanchion had died on the operating table.

That evening, Grace watches as Emil and Danielle leave with a suitcase and decides to follow them. They end up at a huge house which turns out to be the "madhouse" Mrs. Collier talked about.

Danielle is obviously unhappy to be back and Emil has to drug her to calm her down. Through a window, Grace sees him pull the murder weapon out of his pocket, wrapped in plastic.

Grace sneaks in to use the telephone and is approached by one of the patients. The woman is clearly unbalanced, telling Grace that germs travel through the telephone wires and that's how she got sick. Her screaming gets the attention of one of the workers. Grace identifies herself as a reporter and demands to meet with the head doctor.

Of course, that doctor is Emil Breton and he pretends that Grace is a patient who was brought in the previous night. "Hello Margaret, why aren't you in your room?" he asks. Grace pleads with the other doctors to go to her car and get her ID. However, Emil's ploy works and she's restrained and put under hypnotherapy.

Under hypnosis, she's told to repeat the line "there was no body because there was no murder." Danielle is lying in a bed next to her, as Emil makes Grace dream she's the other Blanchion sister. Meanwhile, Danielle relives a harrowing experience.

She recalls becoming pregnant while still attached to Dominique. Her sister became jealous, even going so far as to try and kill the baby with a pair of garden shears. The baby later died from other complications and Emil made plans to finally seperate the twins.

The two women come out of their trance and Danielle tells Emil that Dominique is going to kill him. He tells her she only kept her sister alive in her mind to "reassure herself of her existence."

While copping a feel and kissing her, Danielle's other personality manifests itself. She pushes Emil away and he picks up the knife she used to kill Phillip, reminding her of the murder.

Danielle quietly grabs a scalpel and slashes Emil several times with it. He grabs at her and they both fall on top of Grace, who's still trying to shake off the drug.

Danielle, realizing she has just killed someone she still loves, wraps her arms around her bloodied ex-husband. Grace screams at the sick sight before her.

The authorities arrive and take Dominique away, while Grace's parents try to comfort their daughter.

The next day, Detective Kelly tells Grace that police have Dominique on first degree murder charges for killing Emil. He also says that the "black guy's body" has not turned up. "It was all a ridiculous mistake, there was no body," Grace tells him. The detective apologizes for not believing her at first and even tells her that he knows the body was hidden in the sofa.

Grace doesn't budge, denying that the first murder took place. In Quebec, Joseph Larch is still on the case, having followed the sofa all the way to another country.

Margot Kidder, who was Jennifer Salt's roommate at the time, had been dating Brian De Palma. According to Peter Biskind's Easy Riders, Raging Bulls, the young director presented the Sisters script to the two actresses wrapped as presents under their Christmas tree at the end of 1971.

The film was a nice boost to their stalled careers. Kidder would find her biggest hit five years later as Lois Lane in Superman.

Meanwhile, Salt (who starred in the TV feature Gargoyles in 1972) gained her greatest exposure with a role on the groundbreaking TV comedy Soap at the end of the decade.

The Sisters shoot took eight weeks, on location in New York City. The original budget was $250,000, which increased to a half-million by the time shooting commenced.

For some of the scenes, including the close-up of Emil in the clinic and the dream sequence, De Palma and cinematographer Gregory Sandor used 16mm, which added an eerie, surreal quality. The director had been a huge fan of Roman Polanski and was especially fond of the dream sequence in Rosemary's Baby.

Bernard Herrmann was shown the completed film to see if he would be willing to write the score. (At that point, the opening credits were shown over a plain white background, before shots of fetuses were added.)

De Palma recalls in the September 1973 edition of Filmmakers Newsletter that the cantankerous composer complained that nothing happens in the film for the first 40 minutes.

De Palma explained that illustrated his own point precisely, namely that nothing happens during the first 40 minutes of PSYCHO either. Herrmann's response? "You are NOT Hitchcock; for Hitchcock audiences will wait!"

Hunter: This is a great movie that I remember being shown on TV repeatedly when I was a kid late on Saturday nights. It was scary then and now but I'm also struck by the humorous tone that De Palma sets - the interaction between Grace and Detective Kelley, her mother, and investigator Larch, is all wonderfully written and acted.

Any talk of "plagiarism" is a moot point here. De Palma clearly set out to make a project patterned after Hitchcock's films and it works on every level. In fact, Hitch's work at this point was (to some) underwhelming. So it's fitting that the torch was passed to a new generation.

Jason: Although a solid film on all levels and enjoyable to watch, not necessarily one of my favorites. The presence of Kidder makes all the difference here, though, as she plays to perfection delicate, confused Danielle, her accent realistic and believable. I've always been impressed by De Palma's undeniable strength of talent, but simultaneously let down by his inability to find *new* avenues of storytelling to express that talent.