The movie centers upon the brother and sister pair Tony and Tia, whose surname they initially know only as that of their deceased adoptive parents, Malone. The children are placed in an orphanage, where they face difficulties stemming from their strange psychic/psionic abilities: Tony can psychokinetically move and control inanimate objects with the aid of his harmonica, while Tia can communicate telepathically to Tony, commune empathically with animals, and experience premonitions. Tia also possesses minor telekinetic abilities. She carries a "star case" with her at all times, which eventually reveals a strange map.
Two unrelated young girls who happen to look identical suddenly meet. Amanda Lemmon (Mary-Kate Olsen) is an orphan, and she is about to be adopted by the Butkises, a family whom she doesn't like. She actually wants her child-loving social worker, Diane Barrows (Kirstie Alley), to adopt her instead. Diane would like to do so, but authorities will not let her because of her low salary. Alyssa Callaway (Ashley Olsen) is coming home from her boarding school's piano recital competition, only to find that her wealthy father, Roger (Steve Guttenberg), is about to marry Clarice Kensington (Jane Sibbett) a socialite who threatens to send her soon-to-be stepdaughter to boarding school in Tibet.
Having spent a good deal of time enjoying the company of their newfound family and friends at Witch Mountain and intensively studying and practicing their supernatural powers, Tony and his sister Tia are in need of a vacation. Uncle Bené drops them off in their flying saucer at the Rose Bowl stadium in Los Angeles, California, after which the siblings quickly become separated from each other. A man named Dr. Victor Gannon (Lee) and his assistant Letha Wedge (Davis) happen to see Tony using his powers to save their henchman from certain death. Realizing that Tony has supernatural powers, Dr. Gannon drugs the boy with a tranquilizer shot and takes him back to their laboratory. There, Dr. Gannon successfully tests a new mind-control technology on him. Under its influence, Tony is completely hypnotized and does everything that his kidnappers want him to do, like stealing gold from a museum exhibit and stopping Tia from finding them. With Tony at his robotic bidding, Dr. Gannon hopes to achieve recognition within the scientific community and worldwide power, while Letha merely wants a return on her investment.
Lili, a 19-year-old, returns from holidays and learns that her twin brother Loïc has left the house after a violent argument with their father. Lili had a very strong relationship with her brother and is distraught after having no contact with him at all, concluding that something happened to him.
Pim was born as a twin, conjoined at the stomach with her sister, Ploy. Pim was very sweet and protective of Ploy. However, it was Ploy who threw rocks at a group of children who were taunting them. Pim and Ploy always promised each other to stay together till the end of their lives.
Elliot and Beverly Mantle are identical twins and gynecologists who jointly operate a highly successful clinical practice in Toronto that specializes in the treatment of female fertility problems. Elliot, the more confident and cynical of the two, seduces women who come to the Mantle Clinic. When he tires of them, the women are passed on to the shy and passive Beverly, while the women remain unaware of the substitution.
The Young Girls of Rochefort takes place over the course of one weekend in the seaside town of Rochefort, where a fair is coming to the town square. The story centers on twin sisters Delphine (Deneuve) and Solange (Dorléac) — Delphine teaches ballet classes and Solange gives music lessons for a living, but each longs to find her ideal love and a life outside of Rochefort. When the fair comes to town, Delphine and Solange meet two smooth-talking but kind-hearted carnies, Étienne (George Chakiris) and Bill (Grover Dale).
Nawal Marwan, an immigrant to Canada, succumbs to a stroke she suffers at a community swimming pool, and her two children, a brother and sister, receive her final requests in her will. To fulfill her wishes, they must journey to her birthplace.
Simone, a former rocker, is a dedicated homemaker who works in a city of the suburbs of Lyon. She deals especially with Robert, a former virtuoso accordion languishing in unemployment, and his five children. One day, Robert's wife left him to go to live in Paris with a Cop. Desperate, Robert decided to go to the capital to persuade her to come back. Meanwhile, Simone takes a few days of well-deserved vacation, went to Paris to visit her brother. She then finds herself in the same train compartment as Robert, and she discovered stunned on arrival at Lyon that his five children followed him. She must manage all this smala and can happily rely on the hospitality of her brother Pierrot (a transsexual, named now Rita), to take care of all these people. But Simone, who is secretly in love with Robert, will help him in his research and even get the opportunity to record an album with one of his old friends in the music business .
Chloé est une jeune femme très fragile et en pleine dépression. Elle entreprend alors une psychothérapie. Elle tombe rapidement amoureuse de son thérapeute, Paul, et ses sentiments sont partagés. La jeune femme paraît enfin épanouie. Quelques mois plus tard, le couple décide de s'installer dans un appartement commun. Chloé découvre alors que Paul lui a caché une partie de son identité. Il a en effet un frère jumeau, Louis, qui exerce la même profession que lui ...
It's a seemingly idyllic summer in 1935, and identical twins Niles and Holland Perry play around the bucolic family farm. Holland is an amoral mischief maker, though sympathetic Niles is often caught in their shenanigans. Niles carries a Prince Albert tobacco tin with him containing several secret trinkets, including something mysteriously wrapped in blue wax paper, and the Perry family ring, which had been handed down from their grandfather, through their father, to Holland, the older twin. Niles asks Holland to confirm that the ring is now indeed his. "Cripes yes, I gave it to you," is the response. Niles asks Holland to take the ring and the wrapped object back, but Holland insists "I gave them to you, they're yours now." Their obnoxious cousin Russell, whom the boys call "Piggy Lookadoo" behind his back, finds them in the apple cellar below the barn--a place they are not supposed to play--and happens to see the contents of the tobacco tin, including the ring. Russell cryptically states that the ring was supposed to be buried, and promises to "tell on" Niles to his father, Niles' Uncle George. Uncle George padlocks the door to the apple cellar to keep the kids from playing there, but there is another stairway inside the barn, giving them access to the cellar.
After undergoing cosmetic facial surgery, a mother (Susanne Wuest) comes back home to her modern, isolated lakeside house and her ten-year-old twins, Elias and Lukas (Elias and Lukas Schwarz). Her head is swathed in bandages, with only her eyes and mouth visible. The twins are unnerved with their mother's appearance and are further taken aback when she begins to exhibit strange behavior. She pointedly ignores Lukas and appears to only acknowledge Elias in conversation. Though it is the middle of summer, the mother orders the twins to keep the blinds closed during the day, imposes a strict rule of silence inside the house, and allows them to only play outdoors. The mother also acts cruel and lashes out at Elias physically when he displays mischievous or disobedient acts; something that the boys comment that their mother would never do.
In Poland in 1968, a little girl is shown the stars in the winter sky by her mother, who identifies the Christmas Eve star. In France, a little girl is shown one of the first leaves of spring by her mother, who points out the fine veins running through.
The film opens with Bill Kincaid (Edward Norton) lecturing his class at Brown University about Plato's Socratic dialogues. Meanwhile, Bill's identical twin brother Brady Kincaid (also played by Edward Norton) is living in Oklahoma, growing and selling hydroponic marijuana. Brady is under pressure from local drug lord Pug Rothbaum (Richard Dreyfuss) to expand his sales. Despite needing money to repay a debt to Rothbaum, Brady refuses.
Advertising salesman Philip Woode (Lisle Wilson) is the victim of a prank on a Candid Camera-style television show and wins a dinner for two at a New York restaurant. He takes with him Danielle Breton (Margot Kidder), a naive young French Canadian model and aspiring actress who was hired as part of the prank. At dinner, they are interrupted by Danielle's controlling ex-husband Emil (William Finley), but Philip has him thrown out by security. They arrive to Danielle's Staten Island apartment, but spot Emil waiting outside; Philip pretends to leave to lure him away, then returns through the back entrance and the two make love on the living room sofa.