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.
Tia has fragmented memories of her early childhood, including an accident at sea and a man she later remembers as the children's Uncle Bené (), whom they believe drowned during their rescue.
During a field trip to see a movie, Tia experiences a premonition and warns wealthy attorney Lucas Deranian against a potentially dangerous accident. Deranian informs his employer, millionaire Aristotle Bolt, of the children's unique abilities. Bolt, obsessed with the paranormal, demands that Deranian retrieve the children at all costs. Deranian's detective work leads him to the orphanage, where he poses as Tia and Tony's uncle, though not under the name Bené, and takes them to Bolt's mansion.
Though initially suspicious of Bolt's motives, Tia and Tony are lured in by the wealthy trappings of Bolt's home. Bolt eventually reveals that he has been monitoring the children via a closed-circuit television system and that he and Deranian are fully aware of their unusually strong powers. The night of this revelation, Tia and Tony make an escape, using their abilities to psionically control a wild mustang, guard dogs, and the security fence, as well as using Winkie, Tia's cat, to make the allergic security guard let them pass.
Bolt sends Deranian and a thug, Ubermann, after the children. Tia and Tony hide out in a green-and-white Winnebago motor home owned by a crotchety widower named Jason O'Day (Eddie Albert). Initially negative toward the children, Jason gradually begins to recognize their powers and the truth of their story; Tia's vague memories of a disaster at sea intrigue him. He agrees to take the children on the route indicated by Tia's star case, which leads them to a mountain known as Witch Mountain, home to unexplainable phenomena. Avoiding Bolt, the law, and an incited mob convinced the children are witches, they eventually make their way up Witch Mountain, pursued by Deranian and Ubermann, as well as by Bolt in a helicopter.
As their memories begin to fully return, the children realize their accident at sea did not involve a boat but a spacecraft. Tony and Tia are actually of extraterrestrial origin; the double star emblem on the star case stands for a binary star system where their home planet was located.
Having come to Earth because their own planet was dying, survivors of the journey made their way to Witch Mountain and formed a community to await the surviving children, each pair in possession of a star case to help them find their way to their new home. Tony and Tia are the first to reach their destination. The children are reunited with their Uncle Bené (who survived after all, thanks to an "accommodating" shark whom he'd telepathically asked for help) and board another spacecraft. When Bolt and the others leave in defeat, Jason witnesses the spaceship's return as it flies over him to say a final goodbye.Eddie Albert as Jason O'Day, an embittered widower who decides to travel across the country in his motor home.
Ray Milland as Aristotle Bolt, a ruthless and greedy multi-millionaire obsessed with the paranormal and occult who intends to exploit Tony and Tia's powers to increase his wealth.
Donald Pleasence as Lucas Deranian, a well-to-do attorney who works for Mr. Bolt.
Kim Richards as Tia Malone, a nine-year-old orphan with psychic powers.
Ike Eisenmann as Tony Malone, older brother to Tia, orphan with telekinetic powers.
Walter Barnes as Sheriff Purdey, a sheriff bribed by Bolt to pursue the children.
Reta Shaw as Mrs. Grindley, owner of the orphanage Tia and Tony are sent to after the death of their foster parents, the Malones.
Denver Pyle as Uncle Bené, the children's true uncle.
Alfred Ryder as Astrologer.
Lawrence Montaigne as Ubermann, a henchman who assists Deranian in his pursuit of the siblings.
Terry Wilson as Biff Jenkins.
George Chandler as Grocer.
Dermott Downs as Truck, a child from the orphanage who bullies Tony to the point that Tony reveals his powers.
Don Brodie as Gasoline Attendant.
Paul Sorenson as Sergeant Foss.
Harry Holcombe as Captain Malone.
Sam Edwards as Mate.
Dan Seymour as Psychic.
Eugene Daniels as Cort.
Kyle Richards as young Tia Malone (in "elder Tia's" memories) (uncredited)
Escape to Witch Mountain is based on the novel by Alexander Key. Significant differences from the book include its tone and plot elements. For example, in the book, the children are befriended by Father O'Day, a crusty, old Catholic priest, rather than widower Jason O'Day. The children's ship is shot down, rather than crashed, and the children are olive-skinned, though with light-colored hair, rather than fair-skinned and blond. In the book, Deranian is the main antagonist, and he is working for a shadowy European cabal who are trying to capture the children for their special powers, instead of for Aristotle Bolt. The novel is set along or near the Atlantic coast of the United States, whereas the film was shot along the Pacific coast in California.Carmel, Monterey
Felton, Santa Cruz County
Menlo Park, Peninsula School (formerly the Coleman Mansion)
Pebble Beach, California
The film earned a Total Lifetime Gross at the Domestic North American Box Office of $20,000,000. The film charted on the All time Domestic North American Box Office at Rank No. 145 for 'Rated G' films under the MPAA.
The film earned $8,500,000 in rentals at the North American Box Office.
Escape to Witch Mountain (1975), is the first film in the franchise of the 'Witch Mountain' films. The second and sequel film, Return from Witch Mountain, recast the child lead actors Ike Eisenmann as Tony, and Kim Richards, as Tia. In September 1978, Return from Witch Mountain was released to theaters on a double bill with Escape to Witch Mountain (1975). In 1982, Beyond Witch Mountain was produced as a television movie and broadcast on CBS through Walt Disney. In 1995, Escape to Witch Mountain was produced as a remake television movie, with a different cast and several details changed or omitted, and released as part of The Wonderful World of Disney. A reworked Race to Witch Mountain feature film, with a new telling, directed by Andy Fickman was theatrically released in March, 2009.
Composer Johnny Mandel's score for the film was a limited edition CD release by the Intrada label in 2016.